连接顺序的变化 [英] change in sequence of joins

问题描述

请指导我，如果我在我的SQL查询中更改连接的顺序，结果会受到影响吗？例如我的querry是：

kindly guide me that if i change the sequence on joins in my sql query will the results be affected ? e.g my querry is:

select t1.column , t2.column from table t
join table t2 on t2.col = t.col
join table t1 on t1.col = t2.col
where t.col = value

如果我改变上述查询中的连接序列，如下所示：

if i change sequence of joins in above query like this:

select t1.column , t2.column from table t
join table t1 on t1.col = t.col
join table t2 on t2.col = t1.col
where t.col = value

上述查询的结果是否会发生变化

will there be change in result of both above querries

推荐答案

正常加入它没有'无所谓。但是当你开始使用LEFT OUTER JOIN或RIGHT OUTER JOIN

with a normal join it doesn't matter. But it does matter when you start using LEFT OUTER JOIN or RIGHT OUTER JOIN

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