sq192 standard connection query

Others 2020-10-26 18:13:39 views: null

table of Contents

Equivalent connection

1.多表等值连接的结果为多表的交集部分。
2.n表连接，至少需要n-1个连接条件。
3.多表的顺序没有要求。
4.一般需要为表起别名，起别名后一定要用别名不能用以前的名字。
5.可以搭配前面介绍的所有句子使用，比如排序，分组，筛选。

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Non-equivalent join

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Self-connection

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Origin blog.csdn.net/qq_46527915/article/details/109009419
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