这两年来，OCP的071考试不像以前那么稳定了，总是不断的有新考题出现，增加了071考试的难度，对此，我们对071考试的原题进行了收集，并由专业人员给出了答案，分享给大家。
--------------------------------------------
071最新题库-第51题、choose the best answer:
Evaluate the following SQL statement:
SQL> SELECT cust_id, cust_last_name
FROM customers
WHERE cust_credit_limit IN
(select cust_credit_limit
FROM customers
WHERE cust_city ='Singapore');
Which statement is true regarding the above query if one of the values generated by the subquery is NULL?
A) It ignores the NULL value and generates output for the other values produced by the subquery.
B) It produces an error.
C) It generates output for NULL as well as the other values produced by the subquery.
D) It executes but returns no rows.
Answer：A
(解析，子查询中如果有出现某行值为 null，则忽略该行，其它的正常处理，原来 051 的考题。
类似的语句：
select ename from emp where empno in (select mgr from emp);
ENAME
----------
FORD
BLAKE
KING
JONES
CLARK
-----------------------------------------------
OCP解析公开课时间：【每周五晚8点】
OCP解析公开课地址：https://ke.qq.com/course/326223
OCP解析群资料分享：1015267481 验证：ocp
另外，除了OCP公开课，OCM题库直播也同步进行中，OCM最新题库大爆料-【每周四晚8点】，【微信群直播】，可以联系咨询老师进群参与
