Bde.DBTables.TUpdateSQL
Delphi
TUpdateSQL = class(TSQLUpdateObject)
C++
class PASCALIMPLEMENTATION TUpdateSQL : public TSQLUpdateObject
Properties
| Type | Visibility | Source | Unit | Parent |
|---|---|---|---|---|
| class | public | Bde.DBTables.pas Bde.DBTables.hpp |
Bde.DBTables | Bde.DBTables |
Description
TUpdateSQL applies cached updates on behalf of queries or stored procedures that can't post updates directly.
Use a TUpdateSQL object to provide SQL statements used to update read-only datasets represented by TQuery or TStoredProc components when cached updates are enabled. A dataset is read-only either by design or circumstance. If a dataset is read-only by design, the application itself does not provide a user interface for updating data, but may institute a programmatic scheme behind the scenes. If a dataset is read-only by circumstance, it indicates that the Borland Database Engine (BDE) returned a read-only result set. This usually happens for queries made against multiple tables. Such queries are, by SQL-92 definitions, read-only.
TUpdateSQL provides a mechanism for circumventing what some developers consider an SQL-92 limitation. It enables a developer to provide INSERT, UPDATE, and DELETE statements for performing separate update queries on otherwise read-only result sets in such a manner that the separate update queries are transparent to the end user.
In practical application, a TUpdateSQL object is placed on a data module or form, and linked to a TQuery or TStoredProc component through that component's UpdateObject property. If the UpdateObject property points to a valid TUpdateSQL object, the SQL statements belonging to the update object are automatically applied when cached updates are applied.