 |
» |
|
|
|
|
|
5.8 How do I terminate a transaction?
Key points
- Transactions are ended with either a
COMMIT WORK or a ROLLBACK WORK statement.
All locks are released when a transaction is ended.
-
COMMIT WORK makes all data modifications made by the transaction permanent.
-
ROLLBACK WORK undoes all operations since the BEGIN WORK statement
was issued. The ROLLBACK WORK statement can be useful under the following situations:
- The SQLCA.SQLCODE indicates an error has occurred. (SQLCA is a special record
variable that is updated by ALLBASE/SQL during every SQL call. It can be used
to programmatically detect whether or not a call executes successfully.)
-
UPDATE, INSERT, or DELETE statements are issued on multiple rows.
It is possible that one of the commands might fail after only some of the
target rows had been operated on, and you want to undo the changes that were
made (restore your data back to a consistent state).
- You provide input indicating that you do not wish to commit the
transaction.
- Only the transaction of the user that issues the
COMMIT WORK or the ROLLBACK
WORK is affected by the statement.
- Transactions can also be rolled back by ALLBASE/SQL without the user
explicitly issuing the
ROLLBACK WORK statement:
- If you RELEASE from a DBEnvironment without issuing a
COMMIT WORK, ALLBASE/SQL
automatically rolls back the transaction.
- If you have an active transaction in ISQL when you issue an
EXIT
command, you will be prompted about whether or not you want to commit the
transaction. ISQL is being friendly by remembering that
a transaction is in progress and asking you how to terminate it before it
implicity issues a RELEASE statement. But if you issue a RELEASE
statement explicity in ISQL while you have an active transaction, you will
receive a message indicating that your transaction was aborted.
- When a soft-crash or a hard-crash occurs, ALLBASE/SQL automatically rolls
back all transactions that were active at the time of the crash.
- When a deadlock occurs, ALLBASE/SQL automatically rolls back one of the
transactions involved in the deadlock.
Page last updated on November 29, 1995
|
|
|
Printable version
