FOR UPDATE Clause in a SELECT Statement
* Locks the rows in the EMPLOYEES table where job_id is SA_REP.
* Lock is released only when you issue a ROLLBACK or a COMMIT.
* If the SELECT statement attempts to lock a row that is locked by another user, the database waits until the row is available, and then returns the results of the SELECTstatement SELECT employee_id, salary, commission_pct, job_id FROM employees WHERE job_id = 'SA_REP' FOR UPDATE ORDER BY employee_id;