Oracle OCP试题解析（33）

ITAA-OCM

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 job FROM emp WHERE job='CLERK' FOR UPDATE OF empno;

SCOTT has opened another session to work with the database. 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) DELETE FROM emp WHERE job='MANAGER';

D) INSERT INTO emp(empno,ename)  VALUES (1289,'Dick') ;

E) SELECT job FROM emp WHERE job='CLERK' FOR UPDATE OF empno;

Answer: A,B,E

SELECT … FROM … FOR UPDATE语句会申请相应行的排他锁以及行所在表的共享锁。

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