Sybase 12.4.2 Manuale Utente

CHAPTER 8    Transactions and Versioning

When you roll back a transaction, you undo all of the operations in that 
transaction. We say that you are rolling back the database, since you are 
returning the database to an earlier state. 

Rollbacks can occur either due to an explicit user request, or automatically.

You use a 

ROLLBACK

 statement to undo any changes to the database since the 

last 

COMMIT

 or 

ROLLBACK

. 

You use a 

ROLLBACK TO SAVEPOINT

statement to undo any changes to the 

database since the 

SAVEPOINT

 you name, or else to the last 

SAVEPOINT

.

Adaptive Server IQ rolls back the database automatically if a user is in a 
transaction and then logs out or disconnects without committing. The rollback 
is to the most recent commit or rollback.

Rollback returns both the main and temporary stores to their former state. It 
also releases locks:

•

Transaction rollback releases all locks held by the transaction.

•

Rollback to a savepoint releases all locks acquired after that savepoint.

Rollback of open cursors deletes all cursor information and closes both hold 
and non-hold cursors:

•

Transaction rollback closes all cursors. It does not matter whether the 
cursor was opened in the transaction being rolled back, or in an earlier 
transaction.

•

Rollback to a savepoint closes all cursors opened after that savepoint.

For more information on cursors, see “Cursors in transactions”. For more 
information on rollback to a savepoint, see “Rolling back to a savepoint”.

In the event of a system failure or power outage, or when you restart the 
database server after it has been stopped, Adaptive Server IQ attempts to 
recover automatically.