OCP-12cCUUG 071题库考试原题及答案解析（13）

Posted 2021-02-09

13、（6-7） choose two
Which two statements are true regarding operators used with subqueries? (Choose two.)
A) =ANY and =ALL operators have the same functionality.
E) The NOT IN operator is equivalent to is NULL.
C) The <ANY operator means less than the maximum.
D) The NOT operator can be used with IN, ANY and ALL operators.
E) The IN operator cannot be used in single-row subqueries.
Answer：CD
（解析：051 曾经出现过，但是当时是单选题，答案是 D，这个语法比较少见。
其实就是把 NOT 放到整个表达式之前，下面条件执行的结果都是一样，考大家的逻辑思维能力：
WHERE NOT col IN (SELECT ...)（也可以是 WHERE col not IN (SELECT ...)）
WHERE NOT col = ANY (SELECT ...)（大于、小于都可以）
WHERE NOT col = ALL (SELECT ...)（大于、小于都可以）
SQL> select deptno from emp
2 where not deptno in (select deptno from dept where deptno=10);
DEPTNO

20
30
30
....
或者：
select deptno from emp
where not deptno = all (select deptno from dept where deptno=10);