SQL 连接

为什么80%的码农都做不了架构师？>>>   

类型	简称	全称	子句
外连接	left join	left outer join	on
	right join	right outer join	on
	full join	full outer join	on
内连接	join	inner join	on
交叉（完全）连接		cross join	where

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常见的等价语句

    select * from tableA join tableB on tableA.id = tableB.id

    ||

    select a.*, b.* from tableA a , tableB b where a.id=b.id

    ||

    select * from tableA cross join tableB where tableA.id = tableB.id

 

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没有where子句的交叉连接将产生连接所涉及的表的笛卡尔积：

    select * from tableA across join tableB

    ||

    select * from tableA,tableB

 

 

 

转载于:https://my.oschina.net/milize/blog/659569