内关联和外关联
1. 内链接
select a.*,b.* from a,b where a.aa=b.bb;
SRE实战 互联网时代守护先锋,助力企业售后服务体系运筹帷幄!一键直达领取阿里云限量特价优惠。等于select a.*,b.* from a inner join b on a.aa=b.bb;
等于select a.*,b.* from a join b on a.aa=b.bb;
2. 外连接
select a.*,b.* from a right join b on a.aa=b.bb;
select a.*,b.* from a left join b on a.aa=b.bb;

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