sq199 standard connection query

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

table of Contents

Inner connection-syntax format

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特点:
1.添加排序、分组、筛选
2.inner可以省略
3.筛选条件放在where后面,连接条件放在on后面，提高分离性，便于阅读。
4.inner join 连接和sq192语法中的等值连接效果是一样的，都是查询多表的交集。

Equivalent connection

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Non-equivalent join

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Self-connection

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Outer join

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Cross connect

关键字 CROSS  JOIN  
笛卡尔乘积

to sum up

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Origin blog.csdn.net/qq_46527915/article/details/109092827
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