更新表中的列并在Oracle中使用inner

UPDATE employees e
SET department_name = (SELECT d.department_name 
                       FROM departments d 
                       WHERE d.department_id = e.department_id)
WHERE EXISTS (SELECT 1 
              FROM departments d 
              WHERE d.department_id = e.department_id);

SELECT s.sid, s.serial# 
FROM v$locked_object lo, dba_objects ao, v$session s 
WHERE ao.object_id = lo.object_id AND lo.session_id = s.sid;
ALTER SYSTEM KILL SESSION 'sid,serial#';

UPDATE employees e
SET department_name = (SELECT d.department_name 
                       FROM departments d 
                       WHERE d.department_id = e.department_id AND ROWNUM = 1)
WHERE EXISTS (SELECT 1 
              FROM departments d 
              WHERE d.department_id = e.department_id);