--测试select... for update为行锁

declare

  CURSOR cur_dept IS SELECT * FROM dept WHERE deptno = 10 FOR UPDATE; 

begin

  FOR r IN cur_dept LOOP

    IF r.dname = 'ACCOUNTING' THEN

      dbms_lock.sleep(120);

      UPDATE dept SET dname = dname || 'ACCOUNTING_NEW' WHERE CURRENT OF cur_dept;

    ELSE

      UPDATE dept SET dname = 'BAD' WHERE CURRENT OF cur_dept;

    END IF;

  END LOOP; 

  COMMIT;

end;

--在该代码执行的过程中,更新deptno = 10,会被阻塞,而更新deptno = 20不受阻塞