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464 Day 12
■ If the KeyViolTableName property has been specified, any rows causing key violation
errors will be placed in it.
■ If the ChangedTableName property has been specified, TBatchMove will move updated
or changed rows to it from the target table rather than discard them.
TDataSource
Module: DBTables Class ancestor: TComponent
The TDataSource component is the link between data-aware controls and the TDataset
components (TTable, TQuery, and TStoredProc). It’s what allows data-aware components to
interact with physical database objects.
Data-aware controls reference a common TDataSource through their DataSource properties.
It, in turn, references the TDataset that supplies them with data. The TDataset supplies data
to the TDataSource, which is then passed to the data-aware controls. When data is modified
in a data-aware control, the change is passed to the TDataSource, which then passes it to the
TDataset.
By abstracting the data control level from the TDataset level, C++Builder allows the
interaction between the TDataset and data-aware controls to be more easily coordinated. It
enables you, for example, to change the TDataset for a number of components without
changing them individually. That is, if you want to change the TDataset to which a form’s
data-aware controls refer, you don’t have to change the controls themselves. Instead, you
change the TDataset property of the TDataSource to which they refer. This three-tiered
approach allows the access of a group of controls to a given TDataset to be more easily
controlled.
Table 12.19 lists the key properties, Table 12.20 lists the key methods, and Table 12.21 lists
the key events for TDataSource.
Table 12.19. TDataSource key properties.
Property Description
Autoedit Determines whether modifying the contents of a data-aware control
automatically starts Edit mode.
Dataset References the TDataset that provides data to this TDataSource.
Enabled Specifies whether the display of associated data controls is updated.
State Returns the state of the linked TDataset component.