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;
 Partial rollback
DELETE FROM emp WHERE empno = 123; SAVEPOINT x; UPDATE emp SET sal = sal * 1.1; ROLLBACK TO SAVEPOINT x; COMMIT;