why 'not in' can not be followed with 'null'

记录一下:

select * from dept_xxx a where a.deptno not in (select distinct b.deptno from emp_xxx b where b.deptno is not null )

not in(列表),列表如果存在null,那么将无返回结果。

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转载自blog.csdn.net/Eric_YS/article/details/52440439
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