SQL内部联接的空值

本文介绍了SQL内部联接的空值的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我有一个加入

SELECT * FROM Y
INNER JOIN X ON ISNULL(X.QID, 0) = ISNULL(y.QID, 0)

这样的Join中的

Isnull会使它变慢.就像有条件加入.是否有类似的解决方法?我有很多记录，其中QID为Null

Isnull in a Join like this makes it slow. It's like having a conditional Join.Is there any work around to something like this?I have a lot of records where QID is Null

任何人都可以解决，无需修改数据

Anyone have a work around that doesn't entail modifying the data

推荐答案

您有两个选择

INNER JOIN x
   ON x.qid = y.qid OR (x.qid IS NULL AND y.qid IS NULL)

或更简单

INNER JOIN x
  ON x.qid IS NOT DISTINCT FROM y.qid

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