OCP 1Z0 051 QUESTION NO: 49

QUESTION NO: 49 

Examine the structure of the EMPLOYEES and NEW_EMPLOYEES tables:

Which DELETE statement is valid?
 
 
A. DELETE    FROM employees WHERE employee_id = (SELECT employee_id FROM employees); 
B. DELETE * FROM employees WHERE employee_id = (SELECT employee_id FROM new_employees); 
C. DELETE    FROM employees WHERE employee_id IN (SELECT employee_id FROM new_employees WHERE name = ‘Carrey’); 
D. DELETE * FROM employees WHERE employee_id IN (SELECT employee_idFROM new_employees WHERE name = ‘Carrey’); 

1、当子查询中可能有多行值时，不能使用 等号 判断，要改为in 或 = (any/some)

SQL> delete from dept where deptno = any(select deptno from emp);3 rows deletedSQL> rollback;Rollback completeSQL> delete from dept where deptno = some(select deptno from emp);3 rows deleted

2、delete 后不能用 *

SQL> delete * from dept;delete * from deptORA-00903: invalid table name

Answer: C