左外部联接和附加的where子句 [英] Left Outer join and an additional where clause

问题描述

我在定义为左外部联接的两个表上有一个联接，以便所有记录都从左表返回，即使它们在右表中没有记录也是如此.但是，我还需要在右侧表中的字段上包含where子句，但是....我仍然希望为左侧表中的每个记录返回左侧表中的一行，即使where子句中的条件不满足.有办法吗?

I have a join on two tables defined as a left outer join so that all records are returned from the left hand table even if they don't have a record in the right hand table. However I also need to include a where clause on a field from the right-hand table, but.... I still want a row from the left-hand table to be returned for each record in the left-hand table even if the condition in the where clause isn't met. Is there a way of doing this?

推荐答案

是的，将条件(称为谓词)放在连接条件中

Yes, put the condition (called a predicate) in the join conditions

   Select [stuff]
   From TableA a
       Left Join TableB b
           On b.Pk = a.Pk
               -- [Put your condition here, like this]
               And b.Column = somevalue

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