sqlservernotin查询没结果

sql server not in 查询没结果Posted on 今天使用SQL Server 时，遇到使用not in 和not exist的查询结果有差异：not in 查询没结果。 原因：not in 遇到null就不工作了。 摘录： SELECT foreignStockId Probably returns aNULL. Try IdStock Descr stock a N

sql server not in 查询没结果 Posted on

今天使用SQL Server 时，网站空间，遇到使用not in 和not exist的查询结果有差异：not in 查询没结果。

原因：not in 遇到null就不工作了。

摘录：

Probably returns a NULL. Try

a NOT IN (x,y,NULL) Will always return no results as it is equivalent to

a<>x and a<>y and a<>NULL which is

true and true and unknown

Which evaluates to unknown under the rules of three valued logic.

I normally use NOT EXISTS for this type of query

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