FireDAC.Phys.Intf.IFDPhysChangeHandler.TrackCommand
Delphi
property TrackCommand: IFDPhysCommand read GetTrackCommand;
C++
__property _di_IFDPhysCommand TrackCommand = {read=GetTrackCommand};
Properties
| Type | Visibility | Source | Unit | Parent |
|---|---|---|---|---|
| property | public | FireDAC.Phys.Intf.pas FireDAC.Phys.Intf.hpp |
FireDAC.Phys.Intf | IFDPhysChangeHandler |
Description
SQL command that represents the data of interest.
You can use this SQL command to subscribe to change notifications. You can also use this command to refresh the content of the change handler. The underlying database management system may or may not support these use cases.
When the underlying database management system supports subscribing to change notifications, and you change the data that this command returns, the event alerter receives a change notification. If the underlying database management system does not support subscribing to change notifications, you may use generic event alerters to implement change notifications. Only Microsoft SQL Server and Oracle support generic event alerters.
Some database management systems support incremental refreshing of content, where only modified records are returned. When you use one of these database management systems, the data that the value of TrackCommand returns is merged into the content of either MergeTable or MergeManager. When you use a database management system that does not support incremental refreshing of content, the complete content is read every time. Only InterBase supports incremental refreshing of content.