EhLib Users Guide

EhLib Users Guide Library of Components – EhLib 5 Developer’s guide EhLib Team 2010 Edition: 1.52 (Changes and additions are highlighted in red color) Introduction ............................................................................................................ 4 Installation ............................................................................................................. 7 Unpacking archive ................................................................................................................... 7 Installing packages................................................................................................................... 8 Installing help files. ................................................................................................................. 9 Using TDBGridEh component ............................................................................. 10 Brief description of TDBGridEh, TDataLink and TDataSet. .................................................. 10 Working with TDBGridEh at design-time. ............................................................................. 10 Panel of detail information for record – RowDetailPanel. ...................................................... 11 RowPanel mode. .................................................................................................................... 12 Working with datain grouping mode. ..................................................................................... 12 TDBGridEh and vertical scrollbar. ......................................................................................... 14 Customizing scrollbars........................................................................................................... 15Using DBGridEh for sorting and filtering data in the DataSet. ............................................... 15 Customizing grid title. ........................................................................................................... 18 Customizing grid footer. ........................................................................................................ 19 Customizing grid cells. .......................................................................................................... 19 Hints and Tooltips ................................................................................................................. 22 Customizing in place editor in grid cell. ................................................................................. 22 Automatically fits the width of the grid columns to the width of the grid client area. .............. 23 3D and flat look. .................................................................................................................... 23 Using properties of TDBGridEh.IndicatorTitle. ..................................................................... 23 Using global properties for TDBGridEh. ................................................................................ 23 Import/Export TDBGridEh data to/from various formats. ...................................................... 26 Other features. ....................................................................................................................... 26 Converting existing TDBGrid component to TDBGridEh. ..................................................... 28 Using TPrintDBGridEh component ...................................................................... 29 Rich text before and after grid ................................................................................................ 29 Features that current version of TPrintDBGridEh is not supported. ........................................ 29 FAQ List: .............................................................................................................................. 29 Using TDBSumList component ........................................................................... 30 Common understanding of TDBSumList. .............................................................................. 30 How it works and why SumList sometimes calculate aggregation values incorrectly.............. 30 Using data-aware edit controls ............................................................................. 31 Common understanding of edit controls. ................................................................................ 31 Working with edit buttons. ..................................................................................................... 31 Using TDBDateTimeEditEh control. ..................................................................................... 31 Using TDBNumberEditEh control. ........................................................................................ 32 Using TDBComboBoxEh control. ......................................................................................... 32 Using TDBLookupComboboxEh control. .............................................................................. 32 Using SpecRow in columns of DBGridEh component and in DBLookupComboBoxEh component. ............................................................................................................................ 33 Using TPropStorageEh and TPropStorageManagerEh components ...................... 34 Introduction in technology of interaction between MemTable and DataDriver. .... 35 TMemTableEh component. .................................................................................. 36 Two working mode of TMemTableEh component. ................................................................ 36 ViewScroll............................................................................................................................. 36 Master/detail relations. ........................................................................................................... 36 Storing records in tree mode (TreeView). .............................................................................. 36 Working with AutoIncrement fields ....................................................................................... 37 Using indexes. ....................................................................................................................... 38 Using shared array of records by several TMemTableEh?s. .................................................... 38 TRefObjectField field type. ................................................................................................... 38 Using maintained aggregates ................................................................................................. 38 Records sorting. ..................................................................................................................... 38 Creation/removing table data in memory in the „stand-alone? mode. ...................................... 39 Working with MemTableEh in the 'with datadriver' mode. ..................................................... 39 Cached updates. ..................................................................................................................... 40 Marking and Returning to Records......................................................................................... 40 Searching in TMemTableEh .................................................................................................. 41 Quick access to the record values. .......................................................................................... 43 Internal objects of TMemTableEh component. ....................................................................... 44 Workig with TMemTableEh at design-time. .......................................................................... 44 TDataDriverEh component................................................................................... 45 TSQLDataDriverEh component. .......................................................................... 46 TSQLDataDriverEh or TXXXDataDriverEh, which one is best to use. ................................ 48 Working with TSQLDataDriverEh and TXXXDataDriverEh at design-time. ....................... 49 Feedbacks and bug reports ................................................................................... 50 Introduction The Library contains components and classes for Borland Delphi versions 5, 6, 7, 8 & 2005 and Borland C++ Builder versions 5 & 6. The Library is intended to increase capacity of the client?s part of the database application by improving interaction between application and users. TDBGridEh component Using TDBGridEh It provides all functionality of TDBGrid and adds several new features as follows: - Allows to select records, columns and rectangle areas. - Provides special titles that can cover several or all columns. - Can have a footer that is able to show sum/count/other field values. - Allows to resize column automatically to fit grid width equal to client width. - Has an ability to change row height and title height. - Allows automatic broken of a single line long title and data rows to a multiline. - Allows title to act as button and, optionally show a sort marker. - Allows to mark titles by sortmarking sings automatically and sort data in DataSet. - Allows to truncate long text with ellipsis in cells. - Allows lookup list to show several fields. - Have an ability to make an incremental search in lookup fields. - Can have frozen nonscrollable columns. - Allows to show DateTime picker for TDateField and TDateTimeField. - Allows to show bitmaps from TImageList depending on field value. - Allows to hide and track horizontal or vertical scrollbars. - Allows to hide columns. - Allows to show 3D frame for frozen, footer and data rows. - Allows to draw memo fields. - Can show multiline inplace editor. - Can have a proportional scrolling for DadaSets independently of dataset?s sequencing. - Allows to show checkboxes automatically for Boolean fields. Allows to show checkboxes for other type of fields. - Has procedures to save and restore layout (visible columns, columns order, columns width, sortmarkers, row height) in/from registry or ini file. - Allows to show hint (ToolTips) for text that don't fit in the cell. - Allows to export data to Text, Csv, HTML, RTF, XLS and internal formats. - Allows to import data from Text and internal formats. - Can sort data in various datasets. - Can filter data in various datasets. TDBLookupComboboxEh component Using edit controls It provides all functionality of TDBLookupCombobox and adds several new features as follows: - Can have flat style. - Allows to assign values as to KeyValue property and as to display Text property. - Allows to hold KeyValue and Text that will not affect to each others values. Drop down list can: - Show titles, - Have sizing grip, - Automatically set width as sum of DisplayWidth of the list fields (Width = -1), - Automatically drops when the user pressed the key. - Can have specified width. Edit button can: - Show DropDown and Ellipsis or Bitmap image. Have additional events: OnKeyValueChanged and OnButtonClick. TDBSumList component Using TDBSumList It is intended for calculating sums and amount of records in a TDataSet with dynamic changes. Component keeps a list of TDBSum objects, which contains types of group operations (goSum or goCount) and name of fields which values need some calculation. (goCount name of field is unnecessary). TPrintDBGridEh component Using TPrintDBGridEh TPrintDBGridEh provides properties and routines for preview and print of TDBGridEh component with several features: - Ability to expand rows vertically until all text is printed. - Ability to scale grid to fit it to the page width. - Ability to print/preview title for grid. - Ability to print/preview page header and page footer where you can specify macros for current page, current date, current time and/or static text. - Automatically print/preview multi-selected area of TDBGridEh if it?s area is not empty. - Ability to print/preview rich text before and after grid. TPreviewBox component TPreviewBox lets you to create a customizable runtime preview. TPrinterPreview object TPrinterPreview lets you to record printable data in buffer for following output them on screen and to printer. TPrinterPreview have all functions and properties as in TPrinter object. You can use TPrinterPreview object similarly to TPrinter except some details. In TPrinter Printer.Canvas.Handle and Printer.Handle is the same but in TPrinterPreview PrinterPreview.Canvas.Handle represents the metafile in that is recored the data and PrinterPreview.Handle represents Printer.Handle. It means that you have to use PrinterPreview.Canvas.Handle for drawing operation (like DrawText, DrawTexteEx, e.t.c.) and use PrinterPreview.Handle for such functions as returning information about printer facilities (GetDeviceCaps, e.t.c.). Global function PrinterPreview returns default PrinterPreview object and shows data in the default preview form. TDBEditEh component Using edit controls represents a single or multi-line edit control that can display and edit data of field in a dataset or can work as non data-aware edit control. TDBDateTimeEditEh component Using edit controls represents a single-line date or time edit control that can display and edit data of TDateTime fields in dataset or can work as a non data-aware edit control. TDBComboBoxEh component Using edit controls represents a single or multi-line edit control that combines an edit box with a scrollable list and can display and edit a field in a dataset or can works as non data-aware combo edit control. TDBNumberEditEh component Using edit controls represents a single-line number edit control that can display and edit a numeric field in a dataset or can work as non data-aware edit control. TPropStorageEh, TIniPropStorageManEh, TRegPropStorageManEh components Using TPropStorageEh These components realize a technology of storing component properties to/from such storages as INI files, Registry etc. TMemTableEh component It is a dataset that holds all data in memory and can get data from TDataDriverEh and return changed records back to the TDataDriverEh. TDataDriverEh component Deliver records from the server to the TMemTableEh. Deliver changed records from TMemTableEh back to the server. TDataSetDriverEh component It is a DataDriver that deliver records in TMemTableEh from other DataSet and deliver changed records from TMemTableEh back to the DataSet. TSQLDataDriverEh component It is a DataDriver that have properties for keeping five SQL expressions and parameters for querying data, removing, insertions, updating and refreshing records. TSQLDataDriverEh by itself can?t request data from server, but it can prepare parameters of the request and have a global event that programmer can write for transferring SQL expression to/from the server. TBDEDataDriverEh component It is a DataDriver that interacts with the DB server using BDE connection. TIBXDataDriverEh component It is a DataDriver that interacts with the DB server using IBX connection. TDBXDataDriverEh component It is a DataDriver that interacts with the DB server using DBX connection. TADODataDriverEh component It is a DataDriver that interacts with the DB server using ADO connection. Installation Below it will be described how to install EhLib under Delphi 6. Uninstall previous or evaluation version of EhLib from Delphi 6 IDE. Remove or copy this files to other directory this files to prevent crossing this and new version of EhLib (Including EhLib.bpl, EhLib.dcp, EhLibXX.bpl, EhLibXX.dcp files). Unpacking archive Unpack EhLib archive. After unpacking you will have next list of directories: Directories of 'EhLib - source include' version: BCB5 Contain source files which are specific for C++ Builder 5. BCB6 Contain source files which are specific for C++ Builder 6. Common Contain source files which are common for all versions of Delphi and C++ Builder. Delphi5 Contain source files which are specific for Delphi 5. Delphi6 Contain source files which are specific for Delphi 6. Delphi7 Contain source files which are specific for Delphi 7. DEMOS Demonstration projects. It use tables from the DEMOS directory and BDE alias "DBDEMOS". LangResources Contain resource files for various languages. DataService Contain files that contain objects that allows to sort data in various types of datasets. ORDERS Contain text files in which described how to register various versions of EhLib. HLP Contain help files. Directories of 'Ehlib - without source' version or 'Ehlib- Evaluation version': BCB5 Contain all binary files which are need for C++ Builder 5. BCB6 Contain all binary files which are need for C++ Builder 6. Common Contain interface part of source files of EhLib. (Only for information, not require for installation.) Delphi5 Contain all binary files which are need for Delphi 5. Delphi6 Contain all binary files which are need for Delphi 6. Delphi7 Contain all binary files which are need for Delphi 7. DEMOS Demonstration projects. It use tables from the DEMOS directory and BDE alias "DBDEMOS". LangResources Contain resource files for various languages. DataService Contain files that contain objects that allows to sort data in various types of datasets. ORDERS Contain text files in which described how to register various versions of EhLib. HLP Contain help files. Create, if need, new directory "EhLib" in your Delphi_X directory. (For instance: C:\Delphi6\EhLib). If you have EhLib - source include version then copy to this directory files from Common and Delphi6 directory of EhLib archive. If you have EhLib - without source version or evaluation version EhLib then copy to this directory files from Delphi6 directory of EhLib archive. By default EhLib contains resource for English language. If you need other languages you can replace original resource files (which already present in C:\Delphi6\EhLib) by the files that is placed in corresponding language directory. If you don't find found directory for necessary language then you need to take files from any existing language directory and change it as you need. Installing packages. Automatic installing: Run Installer\EhLibInstaller.exe program from EhLib archive to install library in Delphi/C++ Builder IDE automatically. In time of installation the program creates folder, copies files, compile required packages and registers packages in the IDE. Manual installing: Run Delphi and use "File\Open..." menu item of Delphi IDE to open the EhLib runtime package C:\Delphi6\EhLib\EhLib60.dpk. In "Package..." window click "Compile" button to compile and build bpl file. By default Delphi place compiled EhLib60.BPL file to the \Projects\Bpl directory and this directory already present in the search PATH. But if you overwrite default BPL directory then you need to put the compiled EhLib60.BPL file into directory that is accessible through the search PATH (i.e. DOS "PATH" environment variable; for example, in the Windows\System directory). After compiling run-time package you must install design-time package DclEhLib60.BPL into the IDE. Use "File\Open..." menu item to open design-time package DclEhLib60.dpk. In "Package..." window click "Compile" button to compile the package and then click "Install" button to register EhLib components on the component palette. EhLib components have to appear on 'EhLib' page of components palette. Instalation note for users who had EhLib 1.X or 2.X: Note that Delphi IDE does not move components to the new default place on components palette when you install new version of same component(s). So if you already have EhLib installed, then after installation new version does not move EhLib components to the 'EhLib' page. To force Delphi IDE to move components to the default place on components palette do next: Open menu: Component->Configure Palette. Select '[All]' line in Pages listbox. Click 'Default Pages' button. Add, (if need) EhLib directory ("C:\Delphi6\EhLib") in Tools->Environment Options->Library-> Library Path. Troubleshooting. Problem: Solution: In compilation time 1. It can be because Delphi have access to units from old version of Delphi shows next error: EhLib. Try to remove old version of EhLib completely. "Unit AAA compiled 2. It can be because your Delphi or C++ Builder Build number is not with different version of equal to Delphi or C++ Builder Build number under which EhLib unit BBB" was compiled. See Build number of Delphi and C++ Builder under which EhLib was compiled below: C++ Builder 5 (Build 12.34) Update Pack 1 Delphi 5 (Build 6.18) Update Pack 1 Delphi 6 (Build 6.163) [Fatal Error] It can be, because you did not copy files from Common and Delphi6 EhLib.dpk(51): File not directories of EhLib archive to the one directory. found: 'DBSumLst.dcu' If you have EhLib - source include version then copy files from Common and Delphi6 directory of EhLib archive to alone directory. Installing help files. Copy EhLib.hlp and EhLib.cnt files from HLP directory of EhLib archive to the Delphi 6 HELP subdirectory. Run Delphi IDE. Select Help|Customize menu to start the OpenHelp application. Add the EhLib.cnt file to the Contents page, add the EhLib.hlp file to the Index and Link pages. Select "File->Save Project" menu. Close OpenHelp application. To check that EhLib help files have been installed correctly, drop DBGridEh component on the form and press F1. Delphi IDE have to open help window with information about TDBGridEh component. If you want to install help files under several Delphi versions simultaneously (or under C++ Builder and Delphi simultaneously) then you have to create a copy of EhLib.hlp and EhLib.cnt for every version of Delphi or C++ Builder with individual files name (For instance for Delphi 6 copy files EhLib.hlp andEhLib.cnt to EhLibD6.hlp and EhLibD6.cnt respectively). Next - need to edit file EhLibD6.cnt. This file contain several ":Include" clause at first lines. Comment (using semicolon sign) lines that don?t contain DELPHI6.OHL word) :BASE EhLib.hlp :TITLE EhLib library ;:Include bcb4.cfg ;:Include bcb5.ohl ;:Include delphi4.cfg ;:Include DELPHI5.OHL :Include DELPHI6.OHL. Copy EhLibD6.hlp and EhLibD6.cnt to Delphi 6 HELP subdirectory and install help files as described above. Using TDBGridEh component Brief description of TDBGridEh, TDataLink and TDataSet. All below texts are equally pertained in both TDBGridEh component and TDBGrid component. A TDBGridEh control lets you to view and to edit records in a dataset as a tabular grid format. TDBGridEh does not store data in itself, it only show data from dataset via TDataLink object. Every database control have internal TDataLink object to interact with dataset. You can connect TDBGridEh to dataset using DataSource property. If you already have used TStringGrid component you can see that data shows in TStringGrid and in TDBGridEh very similarly, but mechanism that uses to show data in TStringGrid and in TDBGridEh are very different. In TStringGrid count of rows is equal to rows in array of strings, while in TDBGridEh (and TDBGrid) count of rows always not more than count of visible rows and although vertical scrollbar can display thumb position regarding the count of record in dataset, In reality, it take information not from grid but directly from dataset. TDataSet doesn't allow us to work with data as with array of data i.e. we can not quickly get value of the field from certain record. Some types of datasets have not even such notion as record number (in such datasets we can only know what we are at the beginning of dataset or at the end of it or somewhere between them. In that case DBGrid shows vertical scrollbar only in three positions). But to have possibility to draw several records simultaneously, TDataLink object allows having buffer of records (record buffer window) for quick random access. DBGrid uses this possibility of datalink and it sets size of record buffer window equal to count of visible rows in the grid. We can not control what record must be first in this buffer, DataLink itself scrolls record buffer window when we navigate through the dataset. And it controls the scrolling of record buffer window so that the active record is always in the record buffer window. It is a reason why the active record changes position when users change thumb position of vertical scrollbar using mouse. Working with TDBGridEh at design-time. TDBGridEh contains rows and columns. Every row is a record in TDataSet. Every column is a field in TDataSet. Columns can be dynamic or static. Dynamic columns are recreated every time when the state of DataSet is changed. State of DataSet can be changed in several cases. It is changed when, for example, DataSet is reopened. When column is recreated, values of column properties are reset to their default values. It is useful to use dynamic columns when the list of fields of DataSet is not known in advance. In the mode of static columns grid itself never recreates columns. At design-time to create static columns you need to double-click on the grid. The Columns Editor window will be open. Press “Add all fields” in this window. Grid will create static column for every DataSet field. To customize properties of column you need to select its name in the The Columns Editor window. You can also select column in Object Inspector by clicking column title in the grid. If grid is connected to DataSource and DataSource is placed on the same Form as grid, then icon of DataSource will be shown in the bottom right corner of the Grid. You can click on the DataSource icon to select DataSource in Object Inspector. In same manner grid can show DataSet. If a DataSet is a TMemTableEh then grid also can show TDataDriver and DataSet which is connected to DataDriver as a ProviderDataSet. Panel of detail information for record – RowDetailPanel. Subproperties of RowDetailPanel property allow you to create and customize the panel of detailed information for grid rows. Panel if detailed information is a special area inside grid where you can put any control from Component Palette on it. At design- time a panel is always opened under the current record. At run-time panel is hidden, and there is a „+? sign at the beginning part of every row. You can click „+? sign to open panel. At once time panel can be opened only for one row. You can also open panel using key combination Ctrl-Down or key „+?. Use Ctrl-Up to return from panel to grid row. Use „*? key to show or hide panel depending on current state. Subproperties of RowDatailPanel propery: Active: Boolean; this propery allows activating panel of detailed information. Width: Integer; width of panel Height: Integer; height of panel ActiveControl: TWinControl; use this property to define control which will be focused when panel is opening. BevelEdges: TBevelEdges, BevelInner: TBevelCut, BevelOuter: TBevelCut, BevelKind: TBevelKind, BevelWidth: TBevelWidth, BorderStyle: TBorderStyle: Use these properties to control border style of panel. Color: TColor; Color of panel ParentColor: Boolean Property defines if it is need to use color of grid as a color of panel. Public Visible: Boolean This property defines if panel is visible. You can set this property at run-time for reading and writing. Use event OnCheckRowHaveDetailPanel to control of panel showing in grid. You can set parameter RowHaveDetailPanel to allow or forbid panel for required record. Use events OnRowDetailPanelHide and OnRowDetailPanelShow to execute special action after panel is hidden or before panel is openened. RowPanel mode. Grid can work in special mode when every cell of grid can be placed under each other and can have individual height. Set RowPanel.Active to True value to activate this mode. At design-time you can place cell, vertical and horizontal size. At run-time the possibility to change position of cell depends on the presence dghColumnMove value in OptionsEh property. Possibility to change vertical size of cell depends on RowSizingAllowed property. When user change cell width, the grid also changes width of adjoined cells which are placed under or above of changing cell and if the right border of these cells match. By analogy when user changes cell height, grid changes height of cells in left or right part of grid if low borders march. Press and hold Shift key to change the size of only single cell. To change cell height of cell you need to move mouse cursor to the low border of the title cell. Mouse cursor will change its image from arrow to two arrows with up and down direction. At this moment press right mouse button and change size. To change position of cell you need to press right mouse button on the title cell and drag it to the required place. Additional subproperies of the RowPanel property: NavKeysNavigationType: TGridRowPanelNavKeysNavigationTypeEh defines the order of navigation over cells in the grid when keys Up, Down, Left, Right are pressed. rpntRowToRowEh - (by default) Keys Up, Down move current cell to next or previouse record of dataset. Keys Left, Rigth worksas Tab and Shift-Tab. rpntCellToCellEh - Keys Up, Down move current cell to under or above last position from the current cell. Keys Left, Rigth move current cell to left or right position from the current cell. TabNavigationType: TGridRowPanelTabNavigationTypeEh defines an order of going through cells of the grid by Tab key rpntUpToDownPriorityEh Go, at first, from top to bottom, than from left to right. rpntLeftToRightPriorityEh Go, at first, from left to right, than from top to bottom. Working with datain grouping mode. Grid allows to group data in memory using columns as a grouping criterions. You can create and change grouping at design-time and at run-time. The grouping works only when grid is connected to dataset of TMemTableEh type. When grid group data it also sort data in MemTableEh to have correspondence of data in the gtid and in the MemTable. The Grid track data in the MemTable and moves records in corresponding groups when data are changed. Use subproperties of Grid.DataGrouping property to control grouping. Use Grid.DataGrouping.GroupLevels property to create structure of grouping. GroupLevels is a collection of TDBGridEhDataGroupLevelEh. Every item of collection corresponds one level of grouping. The key property of the item of collection is the ColumnName property of String type. This property keeps name of the column of field for which the records will be group. Use TColumnEh.Name property to get the name of the column at run-time. Use Font and Color properties of structures? items to control the format of the grouping records. Set Grid.DataGrouping.Active to True to activate the grouping. Set GroupPanelVisible property to True to show the current active structure of the grouping. Special panel will be shown with active items of grouping at the top part of the gird. The element of the grouping collection is active when its ColumnName property holds a name of a column. After activation of grouping panel, you can make and change the grouping structure using drag-n-drop operations. Drag the column title to the grouping panel to group data by this column. In time of forming the tree of grouping, grid creates the new group record when the value of the field of column Column.Field is changed. You can change key value of grouping in the event TDBGridEhDataGroupLevelEh.OnGetKeyValue or TColumnsEh.OnGroupGetKeyValue. Take current value of the key value from the field GroupLevel.Column.Field.Value. Write the changed value to the KeyValue parameter of the event procedure. For example, next event will form tree of grouping that will have only two grouping records ‘Big’ and ‘Small’ for numeric field that have record values that bigger or smaller them 100. procedure TForm1.gridFishColumns6GroupGetKeyValue(Sender: TCustomDBGridEh; Column: TColumnEh; var KeyValue: Variant); begin if Column.Field.AsFloat > 100 then KeyValue := 'Big' else KeyValue := 'Small'; end; Grid uses key value to form string that will be shown in the grouping row. If you changed key value of the grouping, then you likely need to change algorithm that convert key value to display value for display. Write OnGetKeyValueAsText event to do it. Write Grid.OnDataGroupGetRowText and GroupLevels.OnGetGroupRowText to rewrite the algorithm of forming the text that is shown in the grouping row. Use property Grid.DataGrouping.GroupDataTree to access the items of grouping tree. The property have the TGridGroupDataTreeEh type and is inherited form TTreeListEh. The itmes of TTreeListEh class form the tree-type structure of groups and references to DataSet records for the lowest levels of grouping. Use properties FlatVisibleCount and FlatVisibleItem[Index] to access items as a flat list. The flat list FlatVisibleItem contain only items which are in the scope of the expanded nodes. Amount of items in flat array corresponds amount of rows in the grid. Every item of array is a reference to the instance of TGroupDataTreeNodeEh class and defines a node in the grouping tree. Basic properties of this class are: Count: Integer; Amount of nodes in the group. Nodes can be over groups of lower level or references to dataset records. DataGroup: TGridDataGroupLevelEh Reference to item of grouping structure. Not empty if the node is a node of group. DataSetRecordViewNo: Integer. Number of record in MemTableEh. Not empty if the node is a node of the dataset record. Expanded: Boolean. Noe is expanded. Items[Index: Integer]: TGroupDataTreeNodeEh. List of nodes of the lower level. KeyValue: Variant; Level: Integer The number of node level; NodeType: TGroupDataTreeNodeTypeEh. Type of the node. The Node of a group level or a record level. Parent. Указатель на родительскую ветку верхнего уровня. Use Items property of Grid.DataGrouping.GroupDataTree to access the grouping tree as a tree-type structure. Every item of this list is a reference to a tree node of grouping of highest level. Grid.DataGrouping property has next subproperties: Active: Boolean – Set this property to active grouping in the grid. DefaultStateExpanded: Boolean – Define Expanded state for every new group node. GroupLevels: TGridDataGroupLevelsEh – Collection of the grouping structure. Use this property to define template of grouping. GroupPanelVisible: Boolean – Set this property to True to show panel of grouping in the top part of the grid. When the panel is visible you can form the structure of grouping by dragging the title of the column onto this panel. Font: TFont – Defines default Font of grouping records. Color: TColor - Defines default Color of grouping records. Write Grid.OnActiveGroupingStructChanged to take action when the structure of grouping is changed. TDBGridEh and vertical scrollbar. If you work with different types of dataset you can notice that for some types of dataset the DBGrid shows vertical scrollbar correctly, but for other dataset their vertical scrollbar has only three positions independently of record count in dataset. To adjust the vertical scrollbar accommodation the DBGrid uses RecordCount and RecNo property of DataSet component. But some dataset holds -1 in RecordCount and RecNo. DataSet function IsSequenced indicates whether the underlying database table uses record numbers to indicate the order of records. When IsSequenced returns True value, applications can safely use the RecNo property to navigate through records in the dataset and DBGrid can use RecNo property to show thumb position in vertical scrollbar. But when IsSequenced returns False value, DBGrid can not define current record position and it shows vertical scrollbar in three positions. DBGridEh component has possibility to show proportional scrollbar for no sequenced dataset. To do it we need to activate SumList and create list of record bookmars. Set SumList.Active to True and SumList.VirtualRecords to True. SumList will run through dataset and create list of records bookmarks. If you use client/sever technology to access database SumList will force dataset to fetch all records, but this operation can take much time. Keep in mind that VirtualRecords will work only for full relationship bookmarks dataset, it means that DataSet.ComapreBookmark function has to return > 0 if record1 is after record2 (i.e. record to which bookmark1 indicates has to be after record to which bookmark2 indicates). It must return 0 if bookmark1 and bookmark2 points to the same record, and value < 0 if record1 is before record2. TBDEDataSet in most cases support full relationship bookmarks. Customizing scrollbars. To customize scollbars you need to use subprtoperties of HorzScrollBar and VertScrollBar properties. Tracking: Boolean This property … SmoothStep: Boolean … ExtScrollBar: TScrollBar; … Visible: Boolean; … VisibleMode: TScrollBarVisibleModeEh; sbAlwaysShowEh Always shows scrollbar. sbNeverShowEh Never shows scrollbar. sbAutoShowEh Shows or hides scrollbar automatically depending on visible area of grid. If grid is connected to DataSet of TMemTableEh type then on vertical scrolling grid doesn?t change position of active record. Using DBGridEh for sorting and filtering data in the DataSet. DBGridEh can not sort or filter data by itself. But it can pass action for sorting or filtering to the specal object that will do it in DataSet. You can adjust grid for two types of sorting (local or server), using property SortLocal and two type of filtering (also, local and server), but real possibility to apply each type of operation depends on the type of DataSet. For instance, TBDEDataSet does not suppot sorting locally (inside DataSet). so you can not sort data locally when grid is linked to TQuery or TTable. Furthermore, EhLib has only special objects for standard types of DataSet (not for a third party DataSet's). Below you can see a table of special object and DataSet in which those objects can sort or filter data. Unit DataSet Local sorting Server sorting Local filtering Server filtering EhLibBDE TQuery, N Y Y Y TTable EhLibADO TADOQuery, Y Y Y Y TADODataSet EhLibCDS TClientDataSet Y Y Y Y EhLibDBX TSQLQuery, N Y N Y TSQLDataSet EhLibIBX TIBQuery, N Y Y Y TIBDataSet When grid is adjusted for a local filtering, the special object will build expression and assign it to a property Filter of DataSet. So we need also to set Filtered to True value manually. When grid is adjusted for a server filtering, the special object will build SQL:ORDER BY expression and it will replace ORDER BY string in SQL or Command property of DataSet and it will reopen DataSet. When grid is adjusted for a local sorting, the special object will perform a sorting using specific type of DataSet. When the grid is adjusted for a server sorting, the special object will build expression for SQL 'WHERE' clause in SQL string of dataset. It will try to find string that begins from key string '/*Filter*/' in SQL expression and adds filter expression after this string in same line (You can change this key string using global variable - SQLFilterMarker) . So your SQL query must have a line that begins from '/*Filter*/'. For instance: ' select * from table1 where /*Filter*/ 1=1 ' For automatically filtering/sorting data in dataset you need to add one of the units EhLibXXX (EhLibADO, EhLibBDE, EhLibCDS ... depend on the type of dataset where the grid is linked to) to 'uses' clause of any unit of your project. This units have code to register TDatasetFeaturesEh based classes (special object) for respective DataSet's. For other third party DataSet's you have to write and register your own special object or you have to write OnApplyFilter or/and OnSortMarkingChanged events for every required grid. Moreover, you can write OnApplySorting and/or OnApplyFilter for the global variable DBGridEhDataService. These events have TNotifyEvent type where Sender is TCustomDBGridEh. Adjusting grid for sorting data: TDBGridEh allows showing special sortmarking bitmaps (small triangles) in the right part of title cell. In order to automatically mark the title by sortmarking bitmaps you have to add dghAutoSortMarking to OptionsEh property. Add dghMultiSortMarking to OptionsEh in order to allow sortmarking in several columns simultaneously. Set Column.Title.TitleButton to true value for titles which will have possibility to change sortmarkers at run time. Or you can set ColumnDefValues.Title.TitleButton to allow setting sortmarking for all columns where Column.Title.TitleButton is not changed. At runtime, clicking on title will change sortmarking. Holding Ctrl key allows to mark several columns simultaneously. After user changes sormarking grid will call OnSortMarkingChanged event or will pass action to special object, if it is registered. Special object will use Grid.SortLocal property to determine how to sort data: locally or on the server. If you write OnSortMarkingChanged, you can use TDBGrid.SortMarkedColumns property to access the sortmarked columns and TColumnEh.Title.SortMarker property to get state of the sortmarker. Adjusting grid for filtering data: TDBGridEh allows to show special row (under title) where user enters expressions in cells for filtering records in dataset. (Expression in the cell can look like: "1", ">=1", ">1 AND <=5", "%TestStr%"). Set STFilter.Visible to True value to show this special row. AT Run time, when cursor locate in the filter cell, they can press ENTER to apply filter. Grid will parse expression in every not empty filter cell and call TDBGridEh.ApplyFilter. And it calls OnApplyFilter event or passes action to special object, if it is registered. For normally parsing, the expression in cell have to have next format: [Operator1] Operand1 [)] [AND|OR Operator2 Operand2 [)] ] Where OperatorX is one of [ = | <> | != | > | < | >= | <= | ~ | !~ | in ( ] OperandX is a numeric, date or string value or for the operator 'IN' it is a list of values divided by comma. For instance: '1' '>=1' '>1 AND <=5' '~ TestStr%' '!~ TestStr_' 'in (1,2,3,4,5,6) and >100' 'in (Str1,Str2,Str3)' Grid allows to show dropped down list of STFilter in title cells. Set STFilter.Location to stflInTitleFilterEh to active this mode. Use item „(Custom…)? to enter string for filtering or press checkboxes above required values. Global variable DBGridEhShowInTitleFilterBox contain key combination for opening list of filtering values. By default it contains 'Ctrl-T'. When grid is connected to the list of uncial values of column is formed automatically. In addition, list is formed with tacking in account of filter applied in other columns. To form list of values and command for filtering, use next events and methods: Events - TDBGridEh.OnFillSTFilterListValues, TColumnEh.OnFillSTFilterListValues, TDBGridEhCenter.OnFillSTFilterListValues or rewrite method TDatasetFeaturesEh.FillSTFilterListDataValues and register new class MyDatasetFeaturesEh for interaction between grid and dataset. Grid call event OnFillSTFilterListValues every time when it is needed to fill list of StFilter, that have next type: TDBGridEhFillSTFilterListValuesEvent = procedure(Sender: TCustomDBGridEh; Column: TColumnEh; Items: TStrings; var Processed: Boolean) of object; This event presents in TDBGridEh, TColumnEh, TDBGridEhCenter. Every item of Items list must consists of two values: String - Items[i] and Object Items.Objects[i]. Items of object type must be inherited from TPopupListboxItemEh type and they must be declared as global variables. There are already next global variables in DBGridEh: PopupListboxItemEhSortAsc: TPopupListboxItemEhSort; // Item of the list show sorting item Asc and executes sorting in ascending order. PopupListboxItemEhSortDes: TPopupListboxItemEhSort; // Item of the list show sorting item Asc and executes sorting in descending order. PopupListboxItemEhLine: TPopupListboxItemEhLine; // Item of the list show horizontal line. On choosing doesn't perform any actions. PopupListboxItemEhClearFilter: TPopupListboxItemEhSpec; PopupListboxItemEhAll: TPopupListboxItemEhSpec; PopupListboxItemEhEmpties: TPopupListboxItemEhSpec; PopupListboxItemEhNotEmties: TPopupListboxItemEhSpec; PopupListboxItemEhDialog: TPopupListboxItemEhSpec; PopupListboxItemEhApplyFilter: TPopupListboxItemEhSpec; PopupListboxItemEhData: TPopupListboxItemEhData; // Item of the list shows text that defines text of filtering. When it is selected, it is checked by checkbox and it is put in the list of items of values that is needed be in the filtered records. You can call next methods in the event to fill values by default TDBGridEh.DefaultFillSTFilterListValues(Column: TColumnEh; Items: TStrings) TDBGridEh.DefaultFillSTFilterListCommandValues(Column: TColumnEh; Items: TStrings) TDBGridEh.DefaultFillSTFilterListDataValues (Column: TColumnEh; Items: TStrings) Next code show OnSTFilterListValues event where sorting items is deleted from list: procedure TForm1.DBGridEh1FillSTFilterListValues(Sender: TCustomDBGridEh; Column: TColumnEh; Items: TStrings; var Processed: Boolean); var Index: Integer; begin Sender.DefaultFillSTFilterListValues(Column, Items); Index := Items.IndexOfObject(PopupListboxItemEhSortAsc); if Index >= 0 then Items.Delete(Index); Index := Items.IndexOfObject(PopupListboxItemEhSortDes); if Index >= 0 then Items.Delete(Index); Processed := True; end; Now library can fill list of unical values only for DataSet of TMemTableEh type. To fill values when grid is connected to other type of DataSet, it is required rewrite TDatasetFeaturesEh.FillSTFilterListDataValues method and , if it is need, it is required to register class that inherited from TDatasetFeaturesEh. Read information about TDatasetFeaturesEh class in EhLib users guide and EhLibMTE.Pas. New properties STFilterDefaultStringOperator, STFilterDefaultNumberOperator, STFilterDefaultDateTimeOperator, STFilterDefaultBooleanOperator are added in TDBGridEhCenter class. Use this properties to set default operator that will be used when string in the STFilter doesn't containt operator. The operators can be assigend appart for String fields, Numeric fields, DataTime fields and logical fields. Customizing grid title. Complex titles. TDBGridEh allows to create one common title above several columns. See Figure: To do it, set DBGridEh.UseMultiTitle property to True value and fill label of the fields or caption of column title using next rule: every part of text in field label or column title must consist of several parts divided by sign "|", where every common part must be same for several required columns. Other fields or captions must contain same text in the corresponding parts. For example: Field1.DisplayLabel := 'Title1|SubTitle1'; Field2.DisplayLabel := 'Title1|SubTitle2'; or DBGridEh.Columns[0].Title.Caption := 'Title1|SubTitle1'; DBGridEh.Columns[1].Title.Caption := 'Title1|SubTitle2'; Title acts as a button. Set Column.Title.TitleButton to True to make title cells act as a button. You can also write an OnTitleBtnClick event to take specific action when the user clicks on title cell. Show bitmaps in titles. Use TitleImages property of TDBGridEh and ImageIndex property of TcolumnTitleEh to show bitmap in titles instead of caption. Default values for title properties. Use TDBGridEh.ColumnDefValues.Title property to set default values for title properties. Customizing grid footer. Footers and total values. TDBGridEh can display special row (footer) or rows at bottom part. Use FooterRowCount property to specify the number of footer rows in the grid. Use Footer or Footers property of TColumnEh object to specify information which needs to show in footer cells. Footers property is useful when you have more than one footer rows. Footers are a collection of TColumnFooterEh objects. Information from i-th element of collection will be shown in i-th row of footer. In footer cell, it is possible to show: Sum value for the specific field, records count, the value of a specific field or static text. Use property Footer.ValueType or Footers[i].ValueType to specify which type of value will be shown in the footer cell. If ValueType = fvtStaticText, then you also need to set Value property to specify text which will be shown. If ValueType = fvtFieldValue, then you need to set property FieldName to specify the field, value of which will be shown. To force grid to calculate total values you need to activate SumList (Set DBGridEh.SumList.Active to True value). Set TColumnFooterEh.ValueType to fvtSum to show sum value of the column field in the footer cell, you can also specify Column.Footer.FieldName to calculate total value of the other field. Set ValueType to fvtCount to force grid to display count of records in the footer cell. Customizing grid cells. Showing bitmaps in data cells depending on the field values. TDBGridEh allows to show bitmaps from TImageList component depending on the field values. In order to show bitmaps you need: 1. Fill list Column.KeyList property by the possible field values (every value in the separated line) and set Column.ImageList property by the TImageList control that has the bitmaps. Every image in ImageList corresponds to the string line in the KeyList property. You can also set Column.NotInKeyListIndex property to the index of bitmap that will be shown if the field's value does not correspond to any value in the KeyList (for instance you can set index of image for Null field value). At run time you can?t edit cells with bitmaps. Use SPACE key or mouse click to set value from next line of Column.KeyList to the field. Use Shift+SPACE key or Shift+Mouse click to set value from previous line Column.KeyList. You can also set Column.DblClickNextval to True to allow changing values in cell by double mouse clicking. Showing pictures from DataSet fields in the grid cells. TDBGridEh can show graphic data in the grid cell from TBlobField fields that have ftGraphic type. Set DrawGraphicData property in True to force the grid to show images from Graphic fields. Checkboxes for Boolean and non Boolean fields. Grid automatically shows checkboxes for Boolean fields. To show checkboxes for no Boolean fields, fill first line of Column.KeyList property by value (or values) that corresponds to the checked state of the checkbox. Fill second line for non-checked state, and set Column.Checkboxes property to True. One line of KeyList can contain more than one value. In that case every value must be separated by semicolon. Data row height. Use RowHeight and RowLines properties to specify the height of data row. Full height of data row is calculated as height in text lines of RowLines plus RowHeight. Set RowSizingAllowed to True value so that user can change height of row using mouse at run time. Set Column.WordWrap to True value to break a long text in data row to a multiline. In reality, text will be wrapped only when height of row is bigger than height of one text line. Individual height of each data row. TDBGridEh can work in mode when the height of every row is calculated dynamically depending on the text in the grid cells or size of image in the cell (When DrawGraphicData value is True). Include dghAutoFitRowHeight in OptionsEh property to force grid to calculate height for every row. This mode works only when the grid is connected to the DataSet of TMemTableEh type and TMemTableEh is not in TreeView mode. When dghAutoFitRowHeight is included, grid calculates the height of the row dynamically using cell text (TColumnEh.WordWrap property also influence it) and for column the fields of which have ftGraphic type. To avoid surplus recalculation, grid recalculates heights, but not for after every change of properties. For instance, grid does not update heights if the Font property was changed. In such cases it is necessary to call UpdateAllDataRowHeights method. For more flexible calculation of the heights the grid has an OnGetRowHeight event, in which you can specify the height of row. During the event calling, the MemTableEh positions on record and we can calculate the height of this record, so you can use MemTableEh properties to access fields values. Draw memo fields. To draw memo fields as text set DrawMemoText to True. Customize cells font attributes and color. TDBGridEh properties Font and Color describe the font and color which is used to draw cells in the grid. TColumnEh properties Font and Color describe the font and color which is used to draw cells in the specified column. Events to customize cell’s font attributes and color. There are several events that allow you to customize cell?s font attributes and color before the cell data will be drawn. In the time of calling these events the DataSet is positioned on the record that need to draw, so in the events you can access field values using such methods as TDataSet.FieldByName(..).Value. Do not change grid properties or columns properties in these events. It can bring to recirculation of the program. TDBGridEh.OnDrawColumnCell Write OnDrawColumnCell event to overload the standard method of the drawing cell. This event is called after standard drawing, so the information will be drawn above standard-drawn contents of cell. You may print the additional data, using methods of TDBGridEh(Sender).Canvas property. TDBGridEh.OnDrawDataCell Do not write an OnDrawDataCell event handler. OnDrawDataCell is obsolete and included for backward compatibility. TColumnEh.OnAdvDrawDataCell or TDBGridEh.OnAdvDrawDataCell Write this event to draw data in the grid cell. In code of the event we set Processed parameter in True value to define that the process of drawing was performed in event. Otherwise grid will call method for default drawing of cell data. You may, if necessary, change such parameters as ARect or Params. After changing the parameters call Grid.DefaultDrawColumnDataCell method and set Processed to True value. You can also leave Processed parameter in False state and don?t call Grid.DefaultDrawColumnDataCell. In that case, grid will call default drawing procedure using changed parameters. Use Grid.Canvas property to draw data in the cell by yourself. TDBGridEh.OnGetCellParams or TColumnEh.OnGetCellParams Write OnGetCellParams event to set such parameters as Font, cell color or other parameters of cell before cell will be drawn. If it is needed to change parameters only in a specified column then use column event - TColumnEh.OnGetCellParams. In this event you may change Font, Color, Alignment, ImageIndex, Text, checkbox's state and also such properties of a Params parameter as: BlankCell: Boolean. Set this property to true to show cell as an empty cell with 3D border. SuppressActiveCellColor: Boolean. Set this property to forbid the color of active cell to overlay the color that is set in Background property. TextEditing: Boolean. Set this property to forbid showing of cell text editor. These events are also called when grid request Font and Color for inplace editor. If you want to draw data by yourself use OnAdvDrawDataCell event. Default values for column properties. To set default values for column properties use ColumnDefValues property. New created columns will take property values from ColumnDefValues properties and will hold them till first assign new value. Hints and Tooltips Hints and Tooltips are special text hints, which are shown in small additional window (usually in a yellow color) while the mouse is above a specified place of grid. To show Hints and Tooltips in DBGridEh it is required to set ShowHint property to True. Hints usually contain additional information about a data in the cell. Tooltips usually contain a full-text of cell if it doesn?t fit in the cell. To show Tooltips in DBGridEh, use the Column.ToolTips, Column.Title.ToolTips, and Column.Footer.ToolTips properties. Besides, there are events Column.OnDataHintShow and Column.DBGridEh that allow to form Hints for cell dynamically. Use these events to set Text, Font, Colour, Position or the other parameters of hint window for every cell of the grid. These events will be called only if Grid.ShowHint is set in True. During the calling event the grid is positioned on required record. So you can access fields values from dataset. Customizing in place editor in grid cell. Banning of text editing in the cell. Use property column TextEditing to ban text editing in the cell. It is allowed to ban text editing dynamically in the OnGetCellParams event. In the event use Params.TextEditing parameter to allow or ban text editing. Several fields in the dropdown lookup list. Fill olumn.LookupDisplayFields by the list of fields to show several fields in lookup list for lookup fields. Semicolons should separate multiple field names. Name Column.Field.LookupResultField must be present in LookupDisplayFields list. Lookup list with several fields can be applied only for lookup fields. Column with simple lookup values. You can show another text in column depending on field values. Use KeyList and PickList property. KeyList have to contain values which kept in the field and PickList have to contain a values to show corresponding lines. Set Column.NotInKeyListIndex to the index of line from PickList that will be shown if the field value is not contained in the KeyList (for instance you can set index of line for Null field value). Set Column.DblClickNextval to True value to allow user to change value in the cell by double click. Dropdown calendar. For TDateField and TDateTimeField fields Inplace Editor will show dropdown button to show dropdown calendar. Set Column.ButtonStyle to cbsNone to prevent showing the dropdown button. Inplace Editor Color and Font. Inplace Editor takes Color and Font from cell color. Cell takes Color and Font from Column Color and Font, and OnGetCellParams event. Inplace Editor automatically set multiline mode when row height bigger than the height of a text line and property WordWrap for column is True. Automatically fits the width of the grid columns to the width of the grid client area. Set AutoFitColWidths to True value for automatic column resizing for fitting grid width equal to width of grid?s visible part. MinAutoFitWidth property determines the minimum width of grid when grid recalculates columns width. 3D and flat look. Use OptionsEh property to show/hide 3D frame for fixed, frozen, footer and data rows. Use Flat property to show grid in the flat style. Using properties of TDBGridEh.IndicatorTitle. Using properties of the TDBGridEh.IndicatorTitle object you can control the behavior of the grid when the left-top cell is clicked. Set TitleButton property to True value to make top-left cell working as button. When TitleButton is True the properties DropdownMenu and UseGlobalMenu are also taken into consideration. If UseGlobalMenu is True then grid will form the dropped down menu using global property DBGridEhCenter.IndicatorTitleMenus.IndicatorTitleMenus. If DropdownMenu is also assigned then all elements of this menu will be added to the dropped down menu after elements of global menu. Subproperies of IndicatorTitle property: property DropdownMenu: TPopupMenu; Identifies the pop-up menu, which elements will be displayed when IndicatorTitle cell is clicked. property ShowDropDownSign: Boolean default False; Determines whether to display the black triangle in upper left when cell of the grid. property TitleButton: Boolean; Determines whether the upper left cell works as button. property UseGlobalMenu: Boolean default True; Determines whether grid will take into account the DBGridEhCenter.IndicatorTitleMenus property to form drop down menu. Using global properties for TDBGridEh. The Library has a set of global properties and event, which influence all grids that are created in the project. You can adjust this properties or event, for instance, in the main Form of your project, and all grids of the project will change its behaviors according to these properties. To control the global behavior of grids there are global objects such as the TDBGridEhCenter and TDBGridEhStyle type. The First one is used to control the behavior of the grids, the second one is to control the style of grids showing. General information about TDBGridEhCenter class: Use global function DBGridEhCenter to access the elements of the TDBGridEhCenter object: function DBGridEhCenter: TDBGridEhCenter; It returns the global object of the type TDBGridEhCenter, which controls the behavior of all grids. You may inherit TDBGridEhCenter class, rewrite virtual methods and register your object of managing using SetDBGridEhCenter function: function SetDBGridEhCenter(NewGridCenter: TDBGridEhCenter): TDBGridEhCenter; It set new object of management and returns the old object. The Old object, in most cases, is required to destroy. Properties and events of the TDBGridEhCenter class: Properties: property FilterEditCloseUpApplyFilter: Boolean; Determines whether the SubTitleFilter will be applied right after choosing value from dropped down list or always need to press Enter key to apply filter. property IndicatorTitleMenus: TDBGridEhStyleIndicatorTitleMenusEh; Specifies the list of elements, which will be visible in IndicatorTitle of dropped down menu when TDBGridEh.IndicatorTitle.UseGlobalMenu = True and TDBGridEh.IndicatorTitle.TitleButton = True. TDBGridEhStyleIndicatorTitleMenusEh is a set which consists of following values itmVisibleColumnsEh - Display the menu item with list of columns, cliquing on which possible to show or hide column. itmCut - Display Cut menu item itmCopy - Display Copy menu item itmPaste - Display Paste menu item itmDelete - Display Delete menu item itmSelectAll - Display SelectAll menu item Events: OnApplyFilter: TNotifyEvent; This event is called when grid apply SubTitleFilter. Sender parameter is a grid that applies filter. In the handler of event you can call default handler - DBGridEhCenter.DefaultApplyFilter. OnApplySorting: TNotifyEvent; This event is called when grid apply sorting. Sender parameter is a grid that applies sorting. In the event handler you can call default handler - DBGridEhCenter.DefaultApplySorting. OnBuildIndicatorTitleMenu: TDBGridEhBuildIndicatorTitleMenu; This event occurs when grid forms the dropped down menu that appears when mouse is clicked on the upper left cell of grid. Event occurs if TDBGridEh.IndicatorTitle.TitleButton = True. Sender parameter is a grid in which IndicatorTitle button was pressed. PopupMenu parameter is a menu that will is displayed under cell. You can call default handler that build menu items by default: DBGridEhCenter.DefaultBuildIndicatorTitleMenu(Grid, PopupMenu); and then perform additional code, for instance, to add one more menu elements. // Below is an example that demonstrate how to add new menu item in list of IndicatorTitle menus. // Declare global menu item for printing the grid. var DBGridEhPreviewIndicatorMenuItem: TDBGridEhMenuItem; // In public section of main Form declare methods for OnBuildIndicatorTitleMenu event. procedure BuildIndicatorTitleMenu(Grid: TCustomDBGridEh; var PopupMenu: TPopupMenu); // Event procedure that will be call when menu item is selected. procedure MenuEditClick(Sender: TObject); // In TMainForm.OnCreate event of the program, assign the event on that will be form IndicatorTitle menu items. procedure TForm1.FormCreate(Sender: TObject); begin DBGridEhCenter.OnBuildIndicatorTitleMenu := BuildIndicatorTitleMenu; end; // Method Itself. procedure TForm1.BuildIndicatorTitleMenu(Grid: TCustomDBGridEh; var PopupMenu: TPopupMenu); begin // At first it calls the default method of menu building. DBGridEhCenter.DefaultBuildIndicatorTitleMenu(Grid, PopupMenu); // Then create new item. if DBGridEhPreviewIndicatorMenuItem = nil then DBGridEhPreviewIndicatorMenuItem := TDBGridEhMenuItem.Create(Screen); DBGridEhPreviewIndicatorMenuItem.Caption := 'Preview'; DBGridEhPreviewIndicatorMenuItem.OnClick := MenuEditClick; DBGridEhPreviewIndicatorMenuItem.Enabled := True; DBGridEhPreviewIndicatorMenuItem.Grid := Grid; // And add it at the end of the menu list. PopupMenu.Items.Insert(PopupMenu.Items.IndexOf(DBGridEhSelectAllIndicatorMenuItem)+1, DBGridEhPreviewIndicatorMenuItem); end; // The Handler of new menu item. procedure TForm1.MenuEditClick(Sender: TObject); begin PrintDBGridEh1.DBGridEh := TDBGridEh(TDBGridEhMenuItem(Sender).Grid); PrintDBGridEh1.SetSubstitutes(['%[Today]',DateToStr(Now)]); PrintDBGridEh1.Preview; end; OnCellMouseClick: TGridEhCellMouseEvent; type TGridEhCellMouseEvent = procedure (Grid: TCustomGridEh; Cell: TGridCoord; Button: TMouseButton; Shift: TShiftState; X, Y: Integer) of object; This event occurs on mouse clicking in any cell of the grid. Event has such parameters: Grid; coordinates of the cell (Cell); Button, which was pressed on mouse (Button); Shift state of keyboard (Shift) and coordinates of the clicked point inside cell (X, Y). In the handler of event you can call the default handler - DBGridEhCenter.DefaultCellMouseClick. OnIndicatorTitleMouseDown: TGridEhCellMouseEvent; type TGridEhCellMouseEvent = procedure (Grid: TCustomGridEh; Cell: TGridCoord; Button: TMouseButton; Shift: TShiftState; X, Y: Integer) of object; This event occurs when the mouse click on upper left cell of the grid occurs. In the handler of event you can call default handler - DBGridEhCenter.DefaultIndicatorTitleMouseDown. OnLocateText: TLocateTextEventEh; type TLocateTextEventEh = function (Sender: TObject; const FieldName: string; const Text: String; Options: TLocateTextOptionsEh; Direction: TLocateTextDirectionEh; Matching: TLocateTextMatchingEh; TreeFindRange: TLocateTextTreeFindRangeEh): Boolean of object; This event occurs during increment or dialogue searching in the grid. The General information about TDBGridEhStyle class: To access elements the global DBGridEhStyle object use function: DBGridEhStyle: TDBGridEhStyle; function It returns the current object of the type TDBGridEhStyle, which controls imaging of all grids. You can inherit TDBGridEhStyle, overwrite virtual methods controlling image of the grid, and register new object to manage, using next function: function SetDBGridEhStyle(NewGridStyle: TDBGridEhStyle): TDBGridEhStyle; Call this function to set new object of image controlling. It returns old object. In most cases it is necessary to delete old object. Properties of the TDBGridEhStyle class: property LuminateSelection: Boolean default True; This property determines whether need to illuminate the selected area in grid. If LuminateSelection = False then the selected area will be painted by clHighlight color. If LuminateSelection = True then selected area will be painted by method as if you see on the area through the transparent glass of the clHighlight color. property IsDrawFocusRect: Boolean default True; This property determines whether to draw pointed square around the current cell or row in the grid. Import/Export TDBGridEh data to/from various formats. EhLib have a set of functions to export data from DBGridEh to Text, Csv, HTML, RTF, XLS and internal formats. It can write data to stream (TStream object) or to file. Example Pascal: SaveDBGridEhToExportFile(TDBGridEhExportAsText,DBGridEh1,'c:\temp\file1.txt',False); C++: SaveDBGridEhToExportFile(__classid(TDBGridEhExportAsText),DBGridEh1,"c:\\temp\\file1.t xt",false); EhLib have set of functions to import data from Text and internal formats to DBGridEh's dataset. It can read data from stream (TStream object) or from file. Other features. Frozen zone. Frozen zone is columns the left part of the grid that remains unchanged when the grid is scrolled to the left or right direction. Unlike the fixed columns the frozen columns can receive the edit focus. To specify the count of the un-scrolling columns you need to set FrozenCols property. Increment search TDBGridEh allows users to accomplish a special "increment" search in grid columns. When user enter in increment search mode, he can type chars and grid will try to locate text in the current column. Use dghIncSearch and dghPreferIncSearch values (OptionsEh property) to customize increment search in the grid. dghIncSearch value allows to perform incremental search in grid. At run time you can use next keys for incremental searching: Ctrl+F - to begin increment searching. Ctrl+Enter - to search next matching. Ctrl+Shift+Enter - to search prior matching. If dghIncSearch in OptionsEh and column is read only then grid will enter in increment search mode automatically after first key press and will return to normal mode after 1.5 sec. dghPreferIncSearch value determines that the grid will set increment search mode automatically after first key press instead of cell editing. Multiselect TDBGridEh allows to select records, columns and rectangle areas for following operations above the selected area. To customize multiselecting you can use next properties: dgMultiSelect in Options property - Specifies whether the multiselect is allowed. dghClearSelection in OptionsEh property - Specifies whether the selection will be cleared after user move to the next cell. EditActions property - Specifies actions which user can execute above the selection (Copy,Cut,Delete,Paste,SelectAll). AllowedSelections - Specifies the types of selections that is allowed to do (Rows, Columns, Rectangle area, All). Selection property specifies a current multiselection state, selected records, columns or rectangle area and it has properties and functions to access them. Save and restore grid and columns layout to/from registry or ini file. TDBGridEh have set of routines to save and restore grid and columns layout to/from registry or Ini file: RestoreColumnsLayout - Restore Columns Order , Width , SortMarker from registry. RestoreColumnsLayoutIni - Restore Columns Order , Width , SortMarker from the ini file. RestoreGridLayout - Restore Columns Order, Width, Visibility, SortMarker, Sortmarked index and/or row height from registry. RestoreGridLayoutIni - Restore Columns Order, Width, Visibility, SortMarker, Sortmarked index and/or row height from the Ini file. SaveColumnsLayout - Save Columns Order, Width, SortMarker in registry. SaveColumnsLayoutIni - Save Columns Order, Width, SortMarker in the ini file. SaveGridLayout - Save Columns Order, Width, Visibility, SortMarker, Sortmarked index and row height in registry. SaveGridLayoutIni - Save Columns Order, Width, Visibility, SortMarker, Sortmarked index and row height in the Ini file. Converting existing TDBGrid component to TDBGridEh. Although TDBGridEh is not inherited from TCustomDBGrid component, there are many alike properties in TDBGridEh and in TDBGrid. It allows us to convert existing TDBGrid component to TDBGridEh with minimum losses. To convert existing TDBGrid component to TDBGridEh follow next instructions: Open Form with TDBGrid component in Delphi IDE. Open Form as Text (Alt-F12) Rename all TDBGrid objects to TDBGridEh ('object DBGrid1: TDBGrid' -> 'object DBGrid1: TDBGridEh') Switch to view Form back as a Form (Alt-F12) Rename all TDBGrid objects in Form declaration to TDBGridEh ('DBGrid1: TDBGrid;' -> 'DBGrid1: TDBGridEh;' ) Try to recompile project. Using TPrintDBGridEh component TPrintDBGridEh allows printing DBGridEh components on the printer. Select TPrintDBGridEh in Delphi IDE component palette and drop it on a form. Select TDBGridEh component in DBGridEh property. Use Print and Preview procedure to print grid on a printer or to preview grid in a preview Form. Rich text before and after grid TPrintDBGridEh allows to print/preview rich text before and after grid. Use AfterGridText and BeforeGridText to specify text. Using SetSubstitutes method you can substitute text in BeforeGridText and AfterGridText properties upon print/preview process. Features that current version of TPrintDBGridEh is not supported. This version of TPrintDBGridEh does not support next features: TPrintDBGridEh can not print/preview several grids on the single page. FAQ List: Q: How to print/preview grid on page in landscape orientation. A: TPrintDBGridEh doesn?t have special properties to set page orientation. To do it, you need to set orientation of virtual printer before calling Print or Preview procedure. Like this code: uses ......, PrViewEh, Printers. .............. procedure TForm1.bPreviewClick(Sender: TObject); begin PrinterPreview.Orientation := poLandscape; PrintDBGridEh1.Preview; end; Using TDBSumList component Common understanding of TDBSumList. You can use TDBSumList for totaling records in a TDataSet with visible dynamic changes. Set the DataSet field in the dataset for which you want to get and write SumListChanged event to take specific action after TDBSumList has changed. TDBSumList has SumCollection property that represents a container of TDBSum objects. Every TDBSum object represents an element that can hold specific aggregation value. FieldName and GroupOperation determine type of aggregation value, SumValue hold current aggregation value. TDBSumList is embedded in DBGridEh component, so that all below text in equal degrees pertains as to TDBSumList component and to TDBGridEh.SumList property. How it works and why SumList sometimes calculate aggregation values incorrectly. Data-aware controls interact with dataset via TDataLink object. TDataLink does not allow to recalculate aggregation value quickly. For instance when the record is deleted from dataset, dataset sends deDataSetChange event to all TDataLink objects, same event is sent when the local filter have been changed. So TDataLink can?t define why it gets this event and when it receives such event then it has to recalculate aggregation values running through whole dataset, even when if only one record was deleted from dataset. SumList doesn?t use these events and after activation, it reassigns following events of the dataset: OnAfterEdit, OnAfterInsert, OnAfterOpen, OnAfterPost, OnAfterScroll, OnBeforeDelete, OnAfterClose. This way allows us to avoid of going through whole dataset when it is not needed. But other problems may appear, such as: Assigning these events at runtime. Deactivate SumList before assigning one of the earlier described events at runtime. Under some conditions SumList can raise exception of access violation. It can happen when SumList tries to assign events back to dataset which had been already deleted. Such situation can appear when SumList (or DBGridEh) and dataset are placed in different forms (or DataModules). In such situation try to deactivate SumList before the Form or DataModule which contains dataset is deleted. SumList can not trace changes in dataset if you use SetRange or ApplyRange methods of TBDEDataSet?s. Call SumList.RecalAll after using such methods. SumList can?t trace changes in master dataset for detail dataset but not for BDE datasets. Call SumList.RecalAll after changing active record in master dataset. In any other case if you see that under some conditions SumList calculates values incorrectly call RecalAll method. If DBGridEh is connected to TMemTableEh then you can show aggregated values in grid using Aggregated fields of TMemTableEh and no need to use TDBGridEh.SumList properties. TMemTableEh uses internal methods to calculate Aggregated fields and doesn?t reassign events. See description of TMemTableEh for detail information about Aggregated fields. Using data-aware edit controls Common understanding of edit controls. EhLib has a set of data-aware edit controls to edit data: TDBEditEh, TDBDateTimeEditEh, TDBComboBoxEh, TDBNumberEditEh and TDBLookupComboboxEh. EhLib doesn?t have not data-aware version of these controls because every control can work as in data-aware mode and not in data-aware mode. The base class for every edit control is TCustomDBEditEh. TCustomDBEditEh encapsulates the behavior that is common for all edit controls for editing text and if it is required for editing a DataSet?s field by introducing methods and properties that provide: Basic text editing functions such as selecting text, modifying selected text, and case conversions. Properties for making it read-only or introducing a password character to hide the actual value. Validity checking using an edit mask. Writing edited text to database field. Showing one or several edit buttons (with variable glyphs: dropdown arrow, Ellipsis arrow, up-down arrows, plus sign, minus sign or custom bitmap) at right part of edit box, Showing image from image list at the left part of the edit box. Application can use Text (String type) and Value (Variant type) properties to get and set string or variant values to controls. Text property is a text that you can see in control. Value property hold value of variant type and can hold values of types depending of control type. It can hold Null value or: String type value for TDBEditEh and TDBComboBoxEh, TDateTime, TDate, TTime, Double type value for TDBDateTimeEditEh, All numeric types value for TDBNumberEditEh, TDBLookupComboboxEh control hold value that depends on type of the field. If control is connected to the field then the assignment data to the Text or Value properties automatically write data to the field. Every control has Flat and AlwaysShowBorder properties to control the border appearance. Working with edit buttons. Every edit control allows to have one or more edit buttons on the right side. You can use EditButton and EditButtons to control them. Using TDBDateTimeEditEh control. TDBDateTimeEditEh represents a single-line date or/and time edit control that can display and edit a date or/and time values. Property Kind determines whether the component is a date editor or/and a time editor (dtkDateEh, dtkTimeEh, dtkDateTimeEh) or custom date-time mask editor (dtkCustomEh). Use EditFormat property to set custom date/time format. You can use next format elements: 'YY', 'YYYY', 'MM', 'DD', 'HH', 'NN', 'SS'. By default TDBDateTimeEditEh build edit mask using ShortDateFormat variable. Edit mask can be by six types: three for four-char year - 'MM/DD/YYYY', 'DD/MM/YYYY', 'YYYY/MM/DD' and three for two-char year 'MM/DD/YY', 'DD/MM/YY', 'YY/MM/DD'. Application can use Text (String type) and Value (Variant type) properties to get and set DateTime type value in TDBDateTimeEditEh. If TDBDateTimeEditEh has dtkDateEh type then it will change only date part of the field. If TDBDateTimeEditEh has dtkTimeEh type then it will change only time part of the field. Using TDBNumberEditEh control. TDBNumberEditEh represents a single-line number edit control that can display and edit numeric values. TDBNumberEditEh builds display text using DisplayFormat property and shows display text when control is not active. Use properties of EditButton object to customize the edit button on the right side of edit control. When EditButton in UpDown style, the control will work as a Spin edit. Use Increment property to specify the value that is added or subtracted from Value when the user calibrates the control. Using TDBComboBoxEh control. TDBComboBoxEh component is an edit box with a scrollable drop-down list attached to it. User can select an item from the list or type it directly into the edit box. TDBComboBoxEh permits a single line and multiple line of text. Use WordWrap property to set TDBComboBoxEh as multiple line editor. Use Items property to access to the list of items (strings) in the list portion of the combo box. Use KeyItems property to access to the list of items (strings) which will be stored in field when Items property is also assigned. When Items and KeyItems properties are filled, then KeyList property have to contain values which will be written in the field, but Items property, in corresponding indexes, has to contain values to display. Use Images property to specify images that will be drawn in the drop-down list and image that will be drawn on the left side of ComboBox. Index of drawing image is taken from ItemIndex property. Using TDBLookupComboboxEh control. TDBLookupComboBoxEh represents a combo box that identifies a set of field(s) values in one dataset with a corresponding set of values from another dataset. To understand 'lookup' concepts see Delphi help, Topic - Displaying and editing data in lookup list and combo boxes. TDBLookupComboboxEh can be of two styles (Style property): csDropDownEh - Application can assign and users can type text which does not contain in data list. csDropDownListEh - Application can assign and users can type text which is only present in data list. If KeyField, ListField, ListSource, DataField and DataSource properties are empty then you can assign KeyValue and Text values which doesn't affect each other. Drop down window takes values from dataset that determines by ListSource property. Drop down list can: Show titles (Captions is took from Field.FisplayLabel property), Show special non-scrolled row in top part of list (SpecRow propery). Have sizing grip (Sizable property), Automaticaly set width of window as sum of DisplayWidth of the list fields (Set Width propery = -1), Automaticaly drops when user presses any key (AutoDrop property). Have specified width (Width property). Using SpecRow in columns of DBGridEh component and in DBLookupComboBoxEh component. The SpecRow property of TDropDownBoxEh or DropDownSpecRow property of TColumnEh holds a TDropDownBoxEh object. TDropDownBoxEh defines attributes of the special row in the dropped down box. TSpecRowEh represents a special row in the top part of dropdown box for lookup fields in column of DBGridEh and in TDropDownBoxEh class of TDBLookupComboboxEh component. This row will be active when lookup field or LookupComboBox has value that is equal to SpecRow.Value property. TSpecRowEh contains next properties: CellsText: String Specifies the text(s) that will be shown in the drop-down window for SpecRow. When dropdown box have more than one columns, use semicolon to separate text for each column. Color: TColor Background color of special row in dropdown box. Font: TFont Font of special row text. Value: Variant Value. Special row is shown as selected (highlighted) when this Value is equal to value of control to which this special row belong to. Visible: Boolean Specify, whether the spec row is active and visible in the DropDown box. ShortCut: TShortCut Specify the shortcut for assigning value of SpecRow.Value property to Control value. ShowIfNotInKeyList: Specify, whether the SpecRow text will be shown in Control if the value Boolean of the control is not in list of key values. Using TPropStorageEh and TPropStorageManagerEh components TPropStorageEh and TPropStorageManagerEh componetns realize technology to store components properties to/from settings storage such as Ini files, Registry etc. Current version of library has components to write/read in/from Ini files and Windows Registry. Base component of this technology is the TPropStorageEh. Place this component in the form, component properties of which you want to save in the storage. Double click on the component during the design-time to open properties storage editor window. In the tree of properties you can select required properties for storing. Properties list is a list of all published properties or declared in DefineProperty function of components with the exclusion of TCollection class properties. Besides the list of all elements of the collection, the tree of properties will contain subproperty. When you select sub-property in the given branch, the component will save corresponding sub-property for each element of the collection. Component TPropStorageEh can write and read property values in the stream. To redirect flow in the storage it is necessary to execute one of the following actions: 1. Place component that is inherited from TPropStorageManagerEh on the form. In this version there are two such components. These are TIniPropStorageManEh and TRegPropStorageManEh. Customize properties of this component and assign component to TPropStorageEh.StorageManager property. 2. Or you can only once write code to register global component - DefaultPropStorageManager. All TPropStorageEh components, in which StorageManager property is not assigned, will use DefaultPropStorageManager manager for redirecting flow of the property values to the storage. Code to register global store manager can look like this: ----------- MainUnit.Pas-------- ...... var IniPropStorageMan: TIniPropStorageManEh; initialization IniPropStorageMan := TIniPropStorageManEh.Create(nil); IniPropStorageMan.IniFileName := 'MyIniFile.Ini'; SetDefaultPropStorageManager(IniPropStorageMan); end. -------------------------------- Introduction in technology of interaction between MemTable and DataDriver. This technology is intended for unified way of loading tabular information from the server to the client with afterward processing these data on the client: editing, sorting, filtrations and unloading changed data back to the server. This technology doesn?t include drivers to access server but it have a set of components and global events to redirect flow of data to/from server using your favorite access engine. The technology is represented by two main components: TMemTableEh - is a dataset that hold data in memory. Its possible to consider it as an array of records. Besides, this dataset: Supports a special interface, which allows DBGridEh component to view and scroll data without moving active record. Allows to fetch data from TDataDriverEh object (DataDriver property). Allows to unload changes back to DataDriver, instantly or postponed (in dependencies of the CachedUpdates property). Allows to create a master/detail relations on the client (filtering record) or on the external source (updating parameters [Params] and requiring data from DataDriver). Allows to sort data, including Calculated and Lookup field. Allows to work in standalone mode. Allows to create structure and fill data at design-time and save data in DFM file of the Form (When DataDriver property is not assigned). Allows to keep record in the manner of trees. Each record can have records-branches and it itself can be an element to other parental record. TDBGridEh component supports to show the tree-type structure of these records. Allows to connect to the internal array of other TMemTableEh (via ExternalMemData property) and work with its data: sort, filter, edit. Has interface for requesting list of all unique values in one column of records array, ignoring local filter. TDBGridEh uses this property for automatic filling a list in DropDownBox of the subtitle filter cell. TDataDriverEh - carry out two tasks: 1. Delivers data to TMemTableEh. 2. Processes changed records of TMemTableEh (writes them in other dataset, or call events for processing the changes in program for passing updates to the server). Furthermore, there are several components that are inherited from TDataDriverEh. These are a TSQLDataDriverEh, that have properties to keep five SQL expressions and parameters to: query data, delete record, insert record, update record and require one record. TSQLDataDriverEh can?t interact with server by itself, but can prepare parameters for request and can call global event to transfer SQL expression for processing in application. There are several components which are inherited from TSQLDataDriverEh and which can send SQL expressions to the server through the corresponding access engine. These are TBDEDataDriverEh, TIBXDataDriverEh, TDBXDataDriverEh and TADODataDriverEh components. TMemTableEh component. Two working mode of TMemTableEh component. There are two working mode of TMemTableEh: „stand-alone? and „with datadriver?. „stand-alone? mode. In „stand-alone? mode TMemTableEh works as independent array of data. Before working with such MemTable it is necessary to create an internal structure of record. For that it is necessary to create external fields (TFields) or field definitions in TMemTableEh and call CreateDataSet method (Or, at design-time, press „Create DataSet? button in Fields editor window). 'with datadriver' mode. The 'with datadriver' mode is activated when TMemTableEh.DataDriver property is assigned. Internal array is created automatically on activation of MemTableEh. Structure of the fields is delivered by DataDriver component. ViewScroll TMemTableEh supports special interface, allowing DBGridEh component to view all data without moving active record. We will call such state as ViewScroll. Master/detail relations. Master/detail relation is a working mode of two datasets when all visible records of one dataset (DetailDataSet) always correspond to one record of other dataset (MasterDataSet). In time of moving in MasterDataSet the DetailDataSet will recreate or filters records so that they will correspond to MasterDataSet record. The correspondence is adjusted using MasterFields and KeyFields properties of DetailDataSet. DetailDataSet always show only the records, which values of the field/fields defined by MasterFields property is equal to values of the fields defined by MasterFields property of the current record of MasterDataSet. TMemTableEh allows to create a master/detail relations on the client side "mdsOnSelfEh" (by filtering record) or on DataProvider "mdsOnProviderEh" (by recreating list of records in DetailDataSet when record in MasterDataset is changed). To adjust TMemTableEh in the master/detail mode use next properties: MasterSource, MasterFields, KeyFields, MasterDetailSide. When MasterDetailSide is mdsOnSelfEh, TMemTableEh will filter records by DetailFields fields using values of MasterDataSet[MasterFields] fields. When MasterDetailSide is mdsOnProviderEh, DetailDataSet will reopen itself, assigning parameters from MasterDataSet[MasterFields]. On opening it will pass parameters to DataDriver. In the mdsOnProviderEh mode the DetailFields are not used. The third state of working "mdsOnSelfAfterProviderEh" is a combination of two preceding. Upon first moving to record in MasterDataSet the DetailDataSet gets records from DataDriver, sending him parameters with values, assigned from MasterSource[MasterFields] and add received records in its internal array of record. Upon next moving on same record in MasterDataSet the DetailDataSet will always only filter records locally. Storing records in tree mode (TreeView). In tree mode the TMemTableEh create node objects (TMemRecViewEh type) for each record in the internal array. Node object have reference to parent record (Rec property) and has a list of child nodes (NodeItems). Adjusting TreeView mode is realized by subproperties of TMemTableEh.TreeList property. TMemTableEh automatically adds new record in the tree, using field values defined by TreeList.KeyFieldName and TreeList.RefParentFieldName properties. When new record is appearances in MemTable, it tries to find Parent record in the list of existing records, it looks throw records trying to find values of the field in KeyFieldName that is equal to the value of the field defined by RefParentFieldName property in the new record. Furthermore, it checks, if this record is a parent for other existing records in array. Building of tree can be speeding up, if you create indexes for fields specified in TreeList.KeyFieldName and TreeList.RefParentFieldName properties. However the maximum speed of building tree is possible to achieve if the records all records will be appended in DataSet in valid sequence. In other words every record must be added in DataSet in same order as it appears in the tree. In last case it is not recommended to create indexes, it can only slow down building of tree. If records appear in DataSet in valid order set FullBuildCheck to False. It will not check if the new record have child records in DataSet. Subproperties of TMemTableEh.TreeList property: Active: Boolean - Defines that TreeView mode is active. In TreeView mode you can access TMemTableEh properties: TreeNodeLevel, TreeNodeExpanded, TreeNodeHasChildren, TreeNodeChildCount for current record. KeyFieldName: String - Holds a name of the key field of record. Child record will refer to parental record with the key determined by the KeyFieldName field. RefParentFieldName: String - Holds a name of the field that contain reference value to a parent record. DefaultNodeExpanded: Boolean - Defines a value of Expanded property for new elements of the tree. DefaultNodeHasChildren: Boolean - Defines a value of HasChildren property for a new elements of the tree. FullBuildCheck: Boolean – Defines if need check if there are Child records in array for new record. Setting this property to False can speed up building of tree, but all child records must be added after parent record. Use next TMemTableEh properties to access state of the tree node for the current record of DataSet: RecView: TMemRecViewEh - a reference to the tree node of the tree, it is available only in tree mode. TreeNodeLevel: Integer - Indicates the level of the node in the tree. TreeNodeExpanded: Boolean - Specifies whether the tree node is expanded. TreeNodeHasChildren: Boolean - Indicates whether a node has any children. TreeNodeChildCount: Integer - An amount of Child elements. Working with AutoIncrement fields TMemTableEh has an AutoIncrement property with InitValue and Step subproperties to work with fields which values are generated by automatic sequence numbers. For such fields property TField.AutoGenerateValue mast be arAutoInc. Values for such fields are generated automatically using internal counter when the new record is appeared in the internal array. Initial value of the counter is assigned by the TMemTableEh.InitValue property. After inserting new record, a value of the counter increases on the number given by the TMemTableEh.Step property. If TMemTableEh is connected to DataDriver then usually values of such fields are generated by the server. To cause TMemTableEh be able to get values of fields generated by the server, it is recommended to use TMemTableEh and TSQLDataDriver (or inherited from it) as follow: Set InitValue property and Step property to -1. Values of AutoIncrement fields will have negative values before sending the new record to the server. Add parameters in TSQLDataDriver.SpecParams property to make SQLDataDriver be able to get values of AutoIncrement fields generated by the server. List of parameters in TSQLDataDriver.SpecParams depends on the type of Server and will be described later. After updates are applied and record new writes to the server, SQLDataDriver will request new value of the counter from server and assign it to the AutoIncrement field on the client. Using indexes. Indexes are used for speeding up searching. In particular it is used to building a tree-type structure of records. Pattern of indexes is assigned in IndexDefs collection. TMemTableEh creates indexes basing on the pattern when it making an internal array of records. It usually happens when DataSet is activated). Using shared array of records by several TMemTableEh’s. TMemTableEh allows to use a same array of records by several TMemTableEh components. But only one main TMemTableEh must be holder of the array. Others will connect to this array using ExternalMemData property use it. Other TMemTableEh components access external data of the main TMemTableEh ignoring local filter of main TMemTableEh. DataDriver property can be assigned only for main MemTable. Sorting and filtration in each MemTableEh components don?t affect to each other. Moving records in TMemTableEh when dghRecordMoving mode is active. Include dghRecordMoving in OptionsEh of DBGridEh component to allow users moving records inside TMemTableEh component. Besides, when TreeList mode is active, DBGridEh allows move records inside tree by changing records and level of node. To move record at run-time, a user has to press the mouse button above the indicator of record and drag it to required place inside the grid (when multiselect is active user has to select records to move before dragging). TRefObjectField field type. MemTableEh unit have code to register new type of field - TRefObjectField. TRefObjectField is intended to keep the pointer to TObject type object and have Value property of TObject type. At design-time choose „RefObjectField? type in form of creating new field to create TRefObjectField field. At run-time in the program you can create a field of this type by assign ftUnknown value to DataType property of FieldDef object. Using maintained aggregates MemTableEh provide support for summarizing data over all records of DataSet. MemTableEh keep aggregated values (such as SUM, COUNT) in TAggregateField field type. At Design-time mode use Fields Editor to create persistent aggregated field. You can bind such fields to TDBEditEh component or to the footer of TDBGridEh. Records sorting. TMemTableEh has two methods of the sorting: Sorting with dynamic supporting of the changes, when the added record is automatically move to the necessary position to support order of the sorting. And sorting without dynamic supporting of the changes. 1. Use the SortOrder property to sort data with dynamic support of the changes. Separate several fields by comma. Add „DESC? after fieldname to sort data in inverse sequence. Sorting occurs at the TRecordsViewEh object, so physically the records doesn?t move inside internal array TRecordsListEh. 2. Use SortByFields procedure to sort data without dynamic support of the changes. The string that define sorting must have same format as for SortOrder property. Sorting occurs on the level of TRecordsListEh, i.e. records are sorted physically in the internal array of data. When you use EhlibMTE unit for automatic sorting in DBGridEh you can use global variable SortInView of Boolean type to define the type of sorting that will be executed when DBGridEh performs sorting after sorting markers in titles of grid are changed. Creation/removing table data in memory in the ‘stand-alone’ mode. MemTableEh allows to create an internal array of records at design-time and at run-time. Before creating the table data, you need to set properties to specify the structure of the table you want to create. In particular, you need to specify structure of the fields of the new array. There are two ways to do this: First way, you can add field definitions to the FieldDefs property. At design time, double-click the FieldDefs property in the Object Inspector to bring up the collection editor. Use the collection editor to add, remove, or change properties of field definitions. At runtime, clear any existing field definitions and then use AddFieldDef method to add each new field definition. For each new field definition, set the properties of the TFieldDef object to specify the desired attributes of the field. Second way, you can use persistent field components instead. At design time, double-click on the dataset to bring up the Fields editor. In the Fields editor, right-click and choose „New Field? command. Describe the basic properties of your field. Once the field is created, you can alter its properties in the Object Inspector by selecting the field in the Fields editor. After creating field definitions or persistent fields, you need to create internal array. At Design-time mode, click right mouse above dataset and choose 'Create DataSet'. This command does not come up in the context menu until you define the whole necessary information. To create an internal array at Run-time, you need to call CreateDataSet method. If DataDriver property is assigned then internal array will be created automatically on activations MemTable. At this case the structure of array MemTable get from DataDriver. In „stand-alone? mode when MemTable is closing it does not delete internal array of records. To close MemTable with simultaneous deleting of all records and structure, use DestroyTable method. Use EmptyTable method to delete all records from MemTable. Working with MemTableEh in the 'with datadriver' mode. If TMemTableEh.DataDriver property is assigned then MemTable works in 'with datadriver' mode. In this case internal array will be created automatically when MemTableEh become active. The structure of array is delivered by the DataDriver component. If FetchAllOnOpen property is True then MemTableEh loads all records from DataDriver on open. If FetchAllOnOpen is False then MemTableEh will not load records until application call Next or FetchRecords methods. Method „Next? checks that cursor is positioned at end of MemTableEh, if not then it fetch next record and move to the next record in provider. Method FetchRecords fetch more records from DataDriver and add it at the end of internal array of MemTable. This method takes one parameter - an amount of records which need to fetch. To fetch all record it is needed to pass „-1? as parameter. When MemTable connected to DBGridEh the Grid calls FetchRecords by itself via IMemTableEh interface to display all visible records in the view area. If CachedUpdates property is False then changes are transferred right after Post method. If CachedUpdates is True then data are not transferred until the ApplyUpdates method is called. Cached updates. TMemTableEh can work in operative or postpone updates. CachedUpdates property defines type if updates. In operative mode of the updates, TMemTableEh sends changed record to c right after application call TMemTableEh.Post method or append new record in TMemTableEh. In the postpone mode the updates aren?t sent to postpone, but are accumulated in the special buffer. Data are not transferred until the client application calls the ApplyUpdates method. To turn on the postpone updates you need set CachedUpdates property to True. ApplyUpdates have a single parameter – MaxErrors. MaxErrors indicates the maximum number of errors that the DataDriver should allow before prematurely stopping update operations. Set MaxErrors to –1 to indicate that there is no limit to the number of errors. Set MaxErrors to 0 to define that whole process of change will be rejected on first error. Records, which renovations have come with errors, have an additional UpdateError property with type of TUpdateErrorEh. To identify type of changing of record you need to use UpdateStatus method and StatusFilter property: UpdateStatus indicates a type of changing of current record in MemTable. It returns one of the following values: usUnmodified - Indicates that the current record haven?t been changed. usModified - Indicates that the record was edited and changed. usInserted - Indicates that the record was added. usDeleted - Indicates that the record was removed. StatusFilter defines filter for different types of records. StatusFilter – is a set that can contains any combination of the following values: usUnmodified – Unmodified records are visible in MemTable. usModified - Modified records are visible in MemTable. usInserted - Added records are visible in MemTable. usDeleted – Deleted record are visible in MemTable. By default, StatusFilter have [usModified, usInserted, usUnmodified] value. So, deleted records are hidden. Method RevertRecord restores an old condition of the current record and values of fields. If record was added in the program, it is deleted from the list. If record was changed then UpdateStatus property is restored to usUnmodified value. Method MergeChangeLog deletes a log of cached changes. All added or changed records get usUnmodified status. Method CancelUpdates cancels all changes and restores old state of records array. Marking and Returning to Records. In addition to moving from record to record in a dataset (or moving from one record to another by a specific number of records), you can mark a particular location in a dataset so that you can return to this location. TDataSet introduces a bookmarking feature that consists of a Bookmark property and five bookmark methods. In TMemTable, bookmarks contain the record number (RecNo property). The Bookmark property. Bookmark gets or sets the current bookmark in a dataset. A bookmark marks a location in a dataset so that an application can easily return to that location quickly. An application can read Bookmark to retrieve the bookmark associated with the current record, and it can change the current record in the dataset by assigning a saved bookmark value to this property. GetBookmark method I do not recommend to use this method, use Bookmark property instead of it. See VCL documentation for detail. GotoBookmark and BookmarkValid method When passed a bookmark, GotoBookmark moves the cursor for the dataset to the location specified in the bookmark. Before calling GotoBookmark, you can call BookmarkValid to determine if the bookmark points to a record. BookmarkValid returns True if a specified bookmark points to a record. CompareBookmarks method You can also call CompareBookmarks to see if a bookmark you want to move to is different from another (or the current) bookmark. If the two bookmarks refer to the same record (or if both are nil), CompareBookmarks returns 0. FreeBookmark method This method is Used in combinations with GetBookamrk. I do not recommend to use this method. See VCL documentation for detail. Searching in TMemTableEh You can search in TMemTableEh using following methods: 1. Locate Locate moves the cursor to the first row matching a specified set of search criteria. In its simplest form, you pass Locate the name of a column to search, a field value to match, and an options flag specifying whether the search is case-insensitive or if it can use partial-key matching. (Partial-key matching is when the criterion string need only be a prefix of the field value.) For example, the following code moves the cursor to the first row in the CustTable where the value in the Company column is "Professional Divers, Ltd.": var LocateSuccess: Boolean; SearchOptions: TLocateOptions; begin SearchOptions := [loPartialKey]; LocateSuccess := CustTable.Locate('Company', 'Professional Divers, Ltd.', SearchOptions); end; If Locate finds a match, the first record containing the match becomes the current record. Locate returns True if it finds a matching record, False if it does not. If a search fails, the current record does not change. The real power of Locate comes into play when you want to search on multiple columns and specify multiple values to search for. Search values are Variants, which means you can specify different data types in your search criteria. To specify multiple columns in a search string, separate individual items in the string with semicolons. Because search values are Variants, if you pass multiple values, you must either pass a Variant array as an argument (for example, the return values from the Lookup method), or you must construct the Variant array in code using the VarArrayOf function. The following code illustrates a search on multiple columns using multiple search values and partial-key matching: with CustTable do Locate('Company;Contact;Phone', VarArrayOf(['Sight Diver','P']), loPartialKey); Locate uses the fastest possible method to locate matching records. If the columns to search are indexed and the index is compatible with the search options you specify, Locate uses the index. 2. Lookup Lookup searches for the first row that matches specified search criteria. If it finds a matching row, it forces the recalculation of any calculated fields and lookup fields associated with the dataset, then returns one or more fields from the matching row. Lookup does not move the cursor to the matching row. It only returns values from it. In its simplest form, you pass Lookup the name of field to search, the field value to match, and the field or fields to return. For example, the following code looks for the first record in the CustTable where the value of the Company field is "Professional Divers, Ltd.", and returns the company name, a contact person, and a phone number for the company: var LookupResults: Variant; begin LookupResults := CustTable.Lookup('Company', 'Professional Divers, Ltd.', 'Company;Contact; Phone'); end; Lookup returns values for the specified fields from the first matching record it finds. Values are returned as Variants. If more than one return value is requested, Lookup returns a Variant array. If there are no matching records, Lookup returns a Null Variant. The real power of Lookup comes into play when you want to search on multiple columns and specify multiple values to search for. To specify strings containing multiple columns or result fields, separate individual fields in the string items with semicolons. Because search values are Variants, if you pass multiple values, you must either pass a Variant array as an argument (for example, the return values from the Lookup method), or you must construct the Variant array in code using the VarArrayOf function. The following code illustrates a lookup search on multiple columns: var LookupResults: Variant; begin with CustTable do LookupResults := Lookup('Company; City', VarArrayOf(['Sight Diver', 'Christiansted']), 'Company; Addr1; Addr2; State; Zip'); end; Like Locate, Lookup uses the fastest possible method to locate matching records. If the columns to search are indexed, Lookup uses the index. 3. FindRec FindRec searches for the first row that matches specified search criteria and return record number. FindRec have the same parameters as the Locate method. When MemTableEh is in tree-view mode the Locate and FindRec methods search records in expanded nodes. To search matches in all nodes you need to use MemTableEh.TreeList.Locate method. This method also expand founded node, so it will be visible in dataset. 4. GotoRec GotoRec moves the cursor to the row passed by the Rec parameter. GotoRec returns True if it finds a record, False if it does not. Quick access to the record values. To get values of the fields from specified record in standard DataSet, it is necessary to move to the required record. This not always suitable since when you move to the record using MoveBy, RecNo, Bookmark methods calls events about changing the record position that can bring about big delays and repaint of the screen. There are several ways in MemTableEh that allow to get values of the fields without activations record position. 1. You can use DisableControls, EnableControls methods to deactivate events about changes in DataSet. Disadvantage of this way is that EnableControls causes event about changes DataSet, that will repaint visual component connected to DataSet. 2. You can use InstantReadEnter, InstantReadLeave methods to enter in InstantRead mode. InstantReadEnter enters in mode of viewing records and moves virtual position to the record determined by the RowNum parameter. After that you can read but don?t change values of record. Each call of InstantReadEnter method, must correspond call InstantReadLeave. InstantReadLeave leave a viewing records mode. In InstantRead mode it is not allowed to change values of record. InstantReadEnter and InstantReadLeave methods do not send events about changing position in DataSet. 3. You can use properties to access internal array of records of MemTableEh. Internal objects allow to access values of record as to the array of data with index. Besides you may addresses to all writing an internal array given disregarding local filter. For access to internal structures of data you need to use following properties of TMemTableEh: RecordsView: TRecordsViewEh – filtered list of records. RecordsView.Rec[Index: Integer]: TMemoryRecordEh – access to certain record in filtered list of records. RecordsView.Count: Integer – Count of records in the filtered list of records. In TreeView mode list have only visible in expanded nodes. RecordsView.MemTableData.RecordsList[Index: Integer]: TMemoryRecordEh – access to certain record in the list of all records. RecordsView.MemTableData.RecordsList.Count – Count of records in list of all records. RecordsView.MemTableData.RecordsList[Index: Integer].DataValues[const FieldNames: string; DataValueVersion: TDataValueVersionEh]: Variant – access to certain value of field in record specified by Index. Copying data from/to another DataSet. TMemTableEh affords the following methods for copying data from/to another DataSat: SaveToDataSet method Copying it own data in another DataSet, specified by Dest parameter. If RecordCount parameter > 0, the copying begins from current record of source DataSet and copy not more then RecordCount record. If RecordCount = 0 then all records will be copied. When copying the MemTable always add records in Dest DataSet. LoadFromDataSet method Loads not more then RecordCount records from Source DataSet to itself. If RecordCount = -1 then it load all record. If Mode parameter is lmCopy then all data will be deleted before loading. If Mode parameter is lmAppend then new records will be added to existing data. UseIfCachedUpdates parameter define that new records gets usInserted status. Internal objects of TMemTableEh component. In most cases to work with data in TMemTableEh it is sufficient to use properties and methods of the TMemTableEh. However in some cases it is necessary to work with data at low level. TMemTableEh component keep records in internal array of records and has seven main objects for processing the internal data: TMemTableDataEh – Internal table of data. Is have two objects: TMTDataStructEh - describes the structure of a table fields and TRecordsListEh containes a list of records of TMemoryRecordEh type. TMTDataStructEh – Describes structure of a table fields. Is have a list of objects that inherited from TMTDataFieldEh class. TMTDataFieldEh – base class that describe field type in internal table array. It is a parent for such types as TMTStringDataFieldEh, TMTNumericDataFieldEh, TMTDateTimeDataFieldEh, TMTBlobDataFieldEh, TMTBooleanDataFieldEh, TMTInterfaceDataFieldEh, TMTVariantDataFieldEh, TMTRefObjectFieldEh. TRecordsListEh – list of records. TMemoryRecordEh – one record in list of record. TRecordsViewEh – hold filtered list of records. Only those records that meet a TMemTableEh.Filter conditions are hold in RecordsView. Hold only records that TMemTableEh.Filter. TMemoryTreeListEh – hold a tree-type list of TMemRecViewEh objects with references to record. Workig with TMemTableEh at design-time. At design-time the double click on the component opens a window of component controling - TMemTableFieldsEditor. It allows: Create fields (TField components) for TMemTableEh. Fill TMemTableEh datas. Load data in TMemTableEh from other DataSet. Create 'stand-alone? array of datas. Clean TMemTableEh. Create new TDataDriver object for TMemTableEh basing on existing DataSet-source of data. Herewith, designer will try to assign DataDriver properties founding on the type DataSet-source. For instance, if you choose to create DataDriver of TSQLDataDriver type and DataSet-source will have a TQuery type, the designer will assign TSQLDataDriver.SelectComand.CommandText property automatically from TQuery.SQL property. TDataDriverEh component. TDataDriverEh is universal data provider for TMemTableEh and a handler of the changes in TMemTableEh. TDataDriverEh is a simplest supplier of datas, it is a agent between TMemTableEh and other DataSet, that can to work with the database. Although many DataSet?s can be connected to DBGrid directly, avoiding TMemTableEh, ligament DBGridEh-DataSource-MemTableEh-DataDriverEh-DataSet is possible to use if you want to use advantages of DBGridEh functioning in ligaments with MemTableEh such as ViewScroll mode, tree-type viewing of data, using same data by the several MemTableEh?s. In the mode of the supplier, TDataDriverEh takes data from DataSet that assigned to ProviderDataSet property, and copies them in TMemTableEh. Before getting first record, MemTableEh requests structure of fields from TDataDriverEh and create internal array of records. TDataDriverEh build structure of fields on basis of fields list of ProviderDataSet. As required, TDataDriverEh takes values of the current record, writes their to a new record of TMemTableEh and goes over to the next record in ProviderDataSet. Furthermore, TDataDriverEh can refresh values of the existing MemTable record from ProviderDataSet (TMemTableEh.RefreshRecord method). TDataDriverEh find record in ProviderDataSet using fields value from KeyFields property and reread values of record in MemTable record. When TDataDriverEh is used as handler of change (TMemTableEh.ApplyUpdates method), it takes a changed record from TMemTableEh, using characteristic KeyFields, finds its position in ProviderDataSet, updates a record in ProviderDataSet, queries it again from ProviderDataSet and returns a record back in TMemTableEh. Events of TDataDriverEh allows to control data which are transferred between TDataDriverEh and TMemTableEh , as well as transfer and process changes from any/to other types source of data. TDataDriverEh have next events: OnBuildDataStruct - write this event to change a structure of fields created when TMemTableEh requests structure of fields. You can call DafaultBuildDataStruct method to build a structure by default. OnProduceDataReader - write this event to return dataset-cursor to read data. You can call DefaultProduceDataReader method to define dataset-cursor by default. By default dataset-cursor will be a ProviderDataSet. OnReadRecord - write this event to assign values of record of new record that delivered to TMemTableEh, or indicate that no more data. You can call DefaultReadRecord method to assign values by default. By default values of record will be assigned from dataset-cursor. If Eof function of dataset-cursor is True then TDataDriverEh indicate that no more data. OnAssignFieldValue - write this event to assign a value of each field of new record that is delivered to TMemTableEh, or when record is refreshing. Use DataValueVersion to determine the mode of assigning: dvvValueEh – when need to assign value for a new record, dvvRefreshValue - when need to assign value for existing record. You can call DefaultAssignFieldValue to assign a value of the field by default. OnRefreshRecord - write this event to assign fresh value of fields at the refreshment of record from the server. You an call DefaultRefreshRecord to assign fresh values by default. OnUpdateRecord - write this event to process updated records in TMemTableEh. Use MemRec.UpdateStatus property to determine the type of changes: Updating, Deleting or Inserting. You can call DefaultUpdateRecord to process updated record by default. By default DataDriver conducts changes in ProviderDataSet. OnUpdateError - write this event to respond certain actions when error is arising in time of processing updates. Following reaction is possible when error is arising: ueaBreakAbortEh Break this and all following operations of changes, exception is not raising. ueaBreakRaiseEh Break this and all following operations of changes, rollback transactions, exception is raising. ueaCountinueEh Ignore an error, does not change a status of a record and continue a performing the rest operations. ueaRetryEh Repeat an operation (You should undertake actions to prevent this error on next time). ueaUpdated CountinueSkip Ignore an error, set record status to Unchanged, continue a performing the rest operations. You can call DefaultUpdateError to execute actions by default. TSQLDataDriverEh component. TSQLDataDriverEh is a universal DataDriver that can interact with server using SQL commands. TSQLDataDriverEh have five objects of the TSQLCommandEh type: SelectCommand, DeleteCommand, InsertCommand, UpdateCommand, GetrecCommand. Each object holds SQL expressions and parameters to execute command to get table data, delete record, insert record, update record and get one record. To execute commands TSQLDataDriverEh calls global event - DefaultSQLDataDriverResolver.OnExecuteCommand. You should write this event to execute SQL expressions on the server and, if need, return DataSet to read data. When TSQLDataDriverEh is used as provider of data, it takes records from DataSet created in DefaultSQLDataDriverResolver.OnExecuteCommand event and writes them in TMemTableEh. On the measure of the requirement it takes given current record, writes them in TMemTableEh and goes over to following record. When TSQLDataDriverEh is used as handler of changes, it takes a changed record from TMemTableEh, and call DefaultSQLDataDriverResolver.OnExecuteCommand event sending DeleteCommand, InsertCommand or UpdateCommand as a parameter. Using TSQLDataDriverEh it is possible change a type of the access to data. Suffice it to rewrite global event - DefaultSQLDataDriverResolver.OnExecuteCommand. TSQLDataDriverEh has a SpecParams property of TStrings type. You may use it to write the special values, which you can use in the DefaultSQLDataDriverResolver.OnExecuteCommand event. This event also is used by TServerSpecOperationsEh object when DefaultSQLDataDriverResolver.ServerSpecOperations property is assigned. List of special values depends of the type of TServerSpecOperationsEh object and values is filled similarly of description in the "Characteristic TXXXDataDriverEh.SpecParams" section. DefaultSQLDataDriverResolver.ServerSpecOperations property has a TServerSpecOperationsEh type. This object is intended to process the special operations before or after ExecuteCommand procedure is performed. TServerSpecOperationsEh is a base class for classes TOracleSpecOperationsEh, TMSSQLSpecOperationsEh, TInterbaseSpecOperationsEh, TInfromixSpecOperationsEh, TDB2SpecOperationsEh, TSybaseSpecOperationsEh and TMSAccessSpecOperationsEh. Each Of these objects can process a SpecParams property in particular to get values of the autoincrement fields that is generated by the server. On the name of the class it is possible to define a type of the server, for which class is intended. For full functioning of TSQLDataDriverEh it is necessary to write DefaultSQLDataDriverResolver.OnExecuteCommand event to execute queries on the server and assign DefaultSQLDataDriverResolver.ServerSpecOperations property by the object that inherited from TServerSpecOperationsEh class. Assigning a ServerSpecOperations property makes sense, if you execute operations of the insertion in tables that have autoincrement field (or sequence objects). The typical code to adjust working of TSQLDataDriverEh can be look as follows: // Below code adjusts working of TSQLDataDriverEh components in the whole Application to access // InderBase server via BDE Engine uses … DataDriverEh, BDEDataDriverEh; type TMainForm = class(TMainForm) Database1: TDatabase; SQLDataDriverEh: TSQLDataDriverEh; … procedure TMainForm.FormCreate(Sender: TObject); begin DefaultSQLDataDriverResolver.OnExecuteCommand := OnExecuteSQLCommand; DefaultSQLDataDriverResolver.ServerSpecOperations := TInterbaseSpecOperationsEh.Create; end; procedure TMainForm.FormDestroy(Sender: TObject); begin DefaultSQLDataDriverResolver.ServerSpecOperations.Free; DefaultSQLDataDriverResolver.ServerSpecOperations := Nil; end; function TMainForm.OnExecuteSQLCommand(SQLDataDriver: TCustomSQLDataDriverEh; Command: TCustomSQLCommandEh; var Cursor: TDataSet; var FreeOnEof, Processed: Boolean): Integer; begin Result := DefaultExecuteBDECommandEh(SQLDataDriver, Command, Cursor, FreeOnEof, Processed, Database1.DatabaseName); end; TSQLDataDriverEh is a base class for TBDEDataDriverEh, TIBXDataDriverEh, TDBXDataDriverEh and TADODataDriverEh. These objects overwrite ExecuteCommand procedure and them can execute SQL expressions on the server and if need returns DataSet to read data. When SQL commands is called, it creates DataSet with type of corresponding type of the access to data. For TBDEDataDriverEh it is a TQuery, for TIBXDataDriverEh it is a TIBXQuery and so on. Furthermore, TBDEDataDriverEh, TIBXDataDriverEh, TDBXDataDriverEh can define TServerSpecOperationsEh object automatically. For TADODataDriverEh it is need to assign DefaultSQLDataDriverResolver. ServerSpecOperations because ADO technology does not allow to define a type of the server. TSQLDataDriverEh have the next events: OnExecuteCommand - write this event to execute SQL expression. You can call TCustomSQLDataDriverEh.DefaultExecuteCommand method to process this event by default. By default TCustomSQLDataDriverEh. DefaultExecuteCommand calls DefaultSQLDataDriverResolver.ExecuteCommand method, which, in turn, call DefaultSQLDataDriverResolver.OnExecuteCommand event. OnGetBackUpdatedValues - write this event to return updated values from server. You can call TCustomSQLDataDriverEh.DefaultGetUpdatedServerValues method to process action by default. TCustomSQLDataDriverEh.DefaultGetUpdatedServerValues call DefaultSQLDataDriverResolver.GetBackUpdatedValues. If it was not processed in DefaultSQLDataDriverResolver then it call InternalGetServerSpecOperations.GetBackUpdatedValues. InternalGetServerSpecOperations returns object of TServerSpecOperationsEh type. Property TXXXDataDriverEh.SpecParams. Property SpecParams kept a list of parameters and values. TXXXDataDriverEh use them when performing SQL expressions. Value of each parameter have to be wrote in the separate line in the format „PARAMETER_NAME =VALUE?. Depending on the type of the server (InterBase, Oracle, MSSQL, Informix) SpecParams can contain the following parameters. On interaction with InterBase server: „GENERATOR? - defines a name of the InterBase generator. DataDriver uses this parameter to get current value of generator after the insertion of new record. „GENERATOR_FIELD? - defines a name of the field, which will be assigned current value of the generator after the insertion of new record. „AUTO_INCREMENT_FIELD? - defines a name of the field, which DataDriver will set AutoIncremet type. It is used on making a structure of the internal array of record. On interaction with Oracle server: „SEQUENCE? - will assign a name of the field Oracle sequences. DataDriver uses this parameter for the reception of the current value of the sequence after the insertion of new record. „SEQUENCE_FIELD? - will assign a name of the field, which will be assigned current value of the sequence after the insertion of new record. „AUTO_INCREMENT_FIELD? - defines a name of the field, which DataDriver will set AutoIncremet type. It is used on making a structure of the internal array of record. On interaction with MSSQL server: „AUTO_INCREMENT_FIELD? - defines a name of the field, which DataDriver will set AutoIncremet type. It is used on making a structure of the internal array of record. On interaction with Informix server: „AUTO_INCREMENT_FIELD? - defines a name of the field, which DataDriver will set AutoIncremet type. It is used on making a structure of the internal array of record. Example of the list of parameters for InterBase server: GENERATOR=EMP_NO_GEN GENERATOR_FIELD=emp_no AUTO_INCREMENT_FIELD=emp_no SQL expression for the insertion of record must contain EMP_NO_GEN generator. insert into employee (EMP_NO, FIRST_NAME) values (:EMP_NO_GEN, :FIRST_NAME) TSQLDataDriverEh or TXXXDataDriverEh, which one is best to use. As TSQLDataDriverEh as one of the TBDEDataDriverEh, TIBXDataDriverEh, TDBXDataDriverEh or TADODataDriverEh components (we will name them as TXXXDataDriverEh) allow to work with database without big number of tunings. For TXXXDataDriverEh it is sufficiently to set database object property (For TBDEDataDriverEh it is a Database property of TDatabase type). TSQLDataDriverEh does not have database object property. To force it works is sufficiently to write DefaultSQLDataDriverResolver.OnExecuteCommand event once to execute queries on server, and assign DefaultSQLDataDriverResolver.ServerSpecOperations property by the object of TServerSpecOperationsEh type to process some specific server operations. DefaultSQLDataDriverResolver is not visual object, so you have to assign an event and property in the program, for example in the OnCreate event of your main form. It is possible to change access Engine to database quickly when you use TSQLDataDriverEh. It is sufficiently rewrite global event - DefaultSQLDataDriverResolver.OnExecuteCommand only. TSQLDataDriverEh and TXXXDataDriverEh works very similar at design-time. When TSQLDataDriverEh component editor is opening you can choose one of design-time types of the database accesses that built-over BDE, ADO, IBX and DBX engines. It is not necessarily that the access engine that you use at design-time will be same as you write in DefaultSQLDataDriverResolver.OnExecuteCommand event. Working with TSQLDataDriverEh and TXXXDataDriverEh at design- time. Double click on TSQLDataDriverEh or TXXXDataDriverEh component opens a dialog editor of TSQLDataDriverEh component. At a design-time TSQLDataDriverEh and TXXXDataDriverEh always use design time copy of object that work with database (it is TDatabase object for DBE engine). If where are not any object was created the system will offer to create a new object. Type of dialog of creating DB Object depend of type of TXXXDataDriverEh. For TSQLDataDriverEh it show dialog where you can choose a type of the access to server (Engine) and service of data processing of server (DB Service). Type of the access defines a engine to access the data and can be one of the following types: BDE, IBX, DBX or ADO. For ADO also need to define "Service a data processing", class that can get a list of DB objects from server. If object that work with database already has been create before then system will offer to choose one of the existing. Window of editing TSQLDataDriverEh have a next controls: 1. Tree list of DB objects. Tables, Views, Procedures, Functions etc. It depends of server type. 2. Lower window of elements of the current object in the tree of objects. 3. Output grid of result of executing the Select expressions. 4. Page of Select expression (TSQLDataDriverEh.SelectSQL) 5. Pages expressions for Inserting, Updating, Deleting, Requesting one record. 6. Page to fill SpecParams property and parameters of dynamic SQL building. Feedbacks and bug reports Don't lazy to notify me about all bugs that you found. But when you send information about errors prepare as more as possible detail info about errors. To check your information I have to have possibility to model same errors on my computer. Include info about OS and service pack, Version of Delphi with Build, Version of EhLib. Also, if possible and you have suspicion that it give additional info, check that error raise on other computers, other OS, other versions of Delphi, other versions of EhLib. The most effective result will be if you send me source code of special demonstration Project that raise it error. Demo Project have to have standard dataset's (not third party) and use tables from DBDEMOS or you can copy data from your dataset to TClientDataSet. Don't send me Demo Projects that contain third party DataSet's or other third party components.