有几种方法可以做到这一点。你是在正确的轨道，但只需要打破WHERE子句中的SELECT语句。



例如：

There are several ways to do it. You are on the right track but just need to break up your SELECT statements in the WHERE clause.

For example:

SELECT *
FROM Contact
WHERE ContactID NOT IN (SELECT ContactID FROM UserDetail)
AND ContactID NOT IN (SELECT ContactID FROM SchoolContact)

或另一种方式：

Or another way:

SELECT *
FROM Contact c 
LEFT JOIN UserDetail d ON c.ConactID = d.ContactID  
LEFT JOIN SchoolContact s ON c.ContactID = s.ContactID
WHERE d.ContactID IS NULL AND s.ContactID IS NULL -- since they are left joined they will be null if no match

甚至：

Or even:

SELECT *
FROM Contact
WHERE ContactID NOT IN (
  SELECT ContactID FROM UserDetail
  UNION 
  SELECT ContactID FROM SchoolContact )

我会测试每个案例，以确保它们在数据库中都不会太慢。

I would test each case to make sure none of them are too slow in your database.

支架有一个小的修正。这将消除错误并显示正确的结果。

Hi,

There is a small correction of bracket. That will get rid of the error and show you the correct result.

select * from [TflStars].[dbo].[Contact]
where [ContactID] NOT IN ( select [ContactID] from [TflStars].[dbo].[UserDetail]) AND [ContactID] NOT IN (select [ContactID] from [TflStars].[dbo].[SchoolContact])

但内部查询可能会变慢下来执行查询。所以你有另外一种选择除和联合的组合。请尝试以下查询。

But inner query may slow down the execution of query. So you have another option of combination of "except" and "union". Please try below query.

select ContactID  from [TflStars]
 EXCEPT
(SELECT ContactID FROM UserDetail
  UNION
 SELECT ContactID FROM SchoolContact
)

如果您有任何疑虑或疑问，或者您仍然面临问题，请与我们联系。



谢谢

Advay Pandya

Please let me know if you have any concern or query or if you are still facing issue.

Thanks
Advay Pandya