MS Access中的歧义左联接 [英] Ambiguous left joins in MS Access

问题描述

我想从T-SQL转换以下查询

I want to convert the following query from T-SQL

SELECT
    * 
FROM
    A                            LEFT JOIN
    B ON A.field1 = B.field1     LEFT JOIN
    C ON C.field1 = A.field2 AND
         C.field2 = B.field2

到Jet SQL.
现在，MS Access不接受模棱两可的查询.我怎样才能做到这一点?我不能将第二个比较放在WHERE子句中.为什么?因为我的情况是我选择的是C中不存在的记录.

to Jet SQL.
Now MS Access does not accept ambiguous queries. How can I do that? I can't put the second comparison in the WHERE clause. Why? Because my scenario is that I am selecting records that does not exist in C.

如何从一个表中选择另一个表中不存在的所有记录?

现在，您如何在MS Access中做到这一点?预先感谢您的时间和专业知识.

Now, how do you that in MS Access? Thanks in advance for your time and expertise.

推荐答案

您需要一个派生表才能在MS Access中工作:

You need a derived table to make this work in MS Access:

SELECT * 
FROM (
   SELECT A.Field1, A.Field2 As A2, B.Field2 
   FROM A 
   LEFT JOIN B ON A.field1 = B.field1) AS x 
LEFT JOIN C ON  x.A2 = C.field1 AND  x.field2= C.field2 

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