How Effects of a Transaction Are Controlled
The COMMIT, ROLLBACK, and SAVEPOINT statements allow control of the effects of a transaction on the database as follows:
• The COMMIT statement makes the changes permanent.
• The ROLLBACK statement undoes the changes made by the transaction.
• The ROLLBACK statement used with the SAVEPOINT statement allows a partial undo of the effects of a transaction.
When a COMMIT statement is issued:
• The DBMS makes all changes resulting from the transaction permanent, terminates the transaction, and drops any locks held during the transaction.
• When a ROLLBACK statement is issued, the DBMS undoes any database changes made by the transaction, terminates the transaction, and releases any locks held during the transaction.