Call this member function after a call to the AddNew or Edit member function.
This call is required to complete the AddNew or Edit operation.
Both AddNew and Edit prepare an edit buffer in which the added or edited data is placed for saving to the data source. Update saves the data. Only those fields marked or detected as changed are updated.
If the data source supports transactions, you can make the Update call (and its corresponding AddNew or Edit call) part of a transaction.
If you call Update without first calling either AddNew or Edit, Update throws a CDaoException. If you call AddNew or Edit, you must call Update before you call MoveNext or close either the recordset or the data source connection. Otherwise, your changes are lost without notification.
When the recordset object is pessimistically locked in a multiuser environment, the record remains locked from the time Edit is used until the updating is complete. If the recordset is optimistically locked, the record is locked and compared with the pre-edited record just before it is updated in the database. If the record has changed since you called Edit, the Update operation fails and MFC throws an exception. You can change the locking mode with SetLockingMode.
Optimistic locking is always used on external database formats, such as ODBC and installable ISAM.
For related information, see the topics "AddNew Method", "CancelUpdate Method", "Delete Method", "LastModified Property", "Update Method", and "EditMode Property" in DAO Help.