MS Access-WHERE IN有效，但WHERE NOT IN失败 [英] MS Access - WHERE IN works, but WHERE NOT IN fails

问题描述

我在MS Access上有以下查询(简体):

I have the following query (simplified) on MS Access:

SELECT * FROM table1 WHERE table1.ID NOT IN (SELECT DISTINCT table1id FROM table2);

我的问题是它不起作用，但是这两个起作用:

My problem is it doesn't work, but these two ones work:

SELECT * FROM table1 WHERE table1.ID IN (SELECT DISTINCT table1id FROM table2);
SELECT * FROM table1 WHERE table1.ID NOT IN (2, 3);

第一个简单地返回一个空集，而我知道我在table1上有ID为1到9的记录，并且表2上仅使用了2和3.

The first one simply returns me an empty set, while I know I have records on table1 with ids ranging from 1 to 9, and only 2 and 3 are use on table 2.

有帮助吗?

推荐答案

通常，IN和NOT in的问题与子选择中的NULL有关.试试这个，看看是否有效:

Generally, the problem with IN and NOT in has to do with NULLs in the subselect. Try this and see if it works:

SELECT *
FROM table1
WHERE table1.ID NOT IN (SELECT DISTINCT table1id FROM table2 where tableid is not null);

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