Where或ON子句中的列顺序（左/右或右/左） [英] Order of columns (left/right, or right/left) on the Where or ON clause

问题描述

研究，似乎无法找到以下问题的答案。 Where子句的列的顺序（左/右）是否会影响执行计划？例如：
$

其中products.num = othertable.column 

< br $> b $ b $
vs

其中othertable.column = products.num 

$


同样的问题也适用于：



< pre class ="prettyprint lang-sql"> products JOIN othertable On products.num = othertable.column

或

 products JOIN othertable On othertable.column = products.num 

两者之间是否有任何性能差异/执行计划？

---

Adrian Hernandez

解决方案

不，它不会影响 生成执行计划。 

Researching, can't seem to find an answer to the following question. Does the order (left/right) of columns on a Where clause affect execution plan? For example :

where products.num = othertable.column

vs

where othertable.column = products.num

The same question would also apply to :

products JOIN othertable On products.num = othertable.column

OR

products JOIN othertable On othertable.column = products.num

Is there any difference performance wise/execution plan between the 2?

---

Adrian Hernandez

解决方案

No, it does not affect the  generated execution plan at all. 

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