Reverts all changes made during the current transaction.
ROLLBACK [TRANSACTION | WORK] [THEN statements] [ELSE statements]
statement reverts all changes made during the current transaction initiated by a BEGIN TRANSACTION
statement. All file changes issued during the transaction are undone, returning the data to the state prior to the BEGIN TRANSACTION
The TRANSACTION or WORK keywords are optional and provides no functionality. They are provided solely for compatibility with other MultiValue vendor products.
You can optionally specify a THEN clause, an ELSE clause, or both a THEN and an ELSE clause. If the transaction rollback is successful, the THEN clause is executed. If the transaction rollback fails, the ELSE clause is executed. The statements
argument can be the NULL
keyword, a single statement, or a block of statements terminated by the END
keyword. A block of statements has specific line break requirements: each statement must be on its own line and cannot follow a THEN, ELSE, or END keyword on that line.
To commit the changes made during the current transaction, issue a COMMIT
statement, rather than a ROLLBACK
After the transaction is closed, program execution continues at the END TRANSACTION
Caché MVBasic supports two sets of transaction statements:
These two sets of transaction statements should not be combined.
Locks and Transactions
File locks and record locks that were taken out during a transaction are released at the end of a transaction. If there are nested transactions, the release of locks taken out during the inner transactions is delayed until the completion of the outermost transaction. This release of locks is part of a successful COMMIT
operation. Locks are described in the LOCK
Unaffected by ROLLBACK
The contents of spooler and form queues, and any print jobs queued or in progress.
The contents of the &PH& file and any spawned PHANTOM (background) processes.
The contents of the &COMO& file used to keep an audit trail of terminal inputs.
The following example performs database operations within a transaction. It sets a variable x, which determines whether the transaction should be committed or rolled back.
PRINT "Before the transaction"
THEN PRINT "Rollback successful"
ELSE PRINT "Rollback failed"
PRINT "This should not print"
PRINT "Transaction resolved"