ROLLBACK( )

Topic group Related topics

Cancels the transaction by undoing all logged changes.

Syntax

ROLLBACK([<database name expC>])

<database name expC>

The name of the database in which to rollback the transaction.

If you began the transaction with BEGINTRANS(<database name expC>), you must issue ROLLBACK(<database name expC>). If instead you issue ROLLBACK( ), dBASE Plus ignores the ROLLBACK( ) statement.

If you began the transaction with BEGINTRANS( ), <database name expC> is an optional ROLLBACK( ) argument. If you include it, it must refer to the same database as the SET DATABASE TO statement that preceded BEGINTRANS( ).

Description

A transaction works by logging all changes. If an error occurs while attempting one of the changes, or the changes need to be undone for some other reason, the transaction is canceled by calling ROLLBACK( ). Otherwise, COMMIT( ) is called to clear the transaction log, thereby indicating that all the changes in the transaction were committed and that the transaction as a whole was posted.

Since new rows have already been written to disk, rows that were added during the transaction are deleted. In the case of DBF tables, the rows are marked as deleted, but are not physically removed from the table. If you want to actually remove them, you can pack the table with PACK. Rows that were just edited are returned to their saved values.

All locks made during a transaction are maintained until the transaction is completed. This ensures that no one else can make any changes until the transaction is committed or abandoned.

For more information on transactions, see BEGINTRANS( ).

OODML

Call the rollback( ) method of the Database object.