185.User SCOTT executes the following command on the EMP table but has not issued COMMIT, ROLLBACK,

185.User SCOTT executes the following command on the EMP table but has not issued COMMIT, ROLLBACK, or any data definition language (DDL) command: SQL> SELECT ename FROM emp WHERE job='CLERK' FOR UPDATE OF empno; SCOTT has opened another session to work with the database instance. Which three operations would wait when issued in SCOTT's second session? (Choose three.) A.LOCK TABLE emp IN SHARE MODE; B.LOCK TABLE emp IN EXCLUSIVE MODE; C.UPDATE emp SET sal=sal*1.2 WHERE job=MANAGER; D.INSERT INTO emp(empno,ename) VALUES (1289,'Harry'); E.SELECT ename FROM emp WHERE job='CLERK' FOR UPDATE OF empno; 答案：ABE 解析：这个select ... for update 是在TX加上了S锁，在TM上增加了SX锁，  因此不能在TX上增加X锁，不能在TM上增加S、SSX、X锁 A：正确，这个相当于TMS锁 B：正确，这个是TM的X锁 C：这里只是TM的SX锁 D：和C一样 E：正确，这里是SX锁，锁的是不同的记录