From Oracle FAQ
ROLLBACK is an SQL command used to undo changes made to the database (restore data to its state prior to the user making changes).
INSERT INTO tab1 VALUES ('val1', 'val2', 'val3'); ROLLBACK;
One can specify savepoints to mark a point in a transaction to rollback to. Example:
DELETE FROM emp WHERE empno = 123; SAVEPOINT x; UPDATE emp SET sal = sal * 1.1; ROLLBACK TO SAVEPOINT x; COMMIT;