廢話不多說，直接上圖秒懂。

t1表的結(jié)構(gòu)與數(shù)據(jù)如下：

inner join

select * from t1 inner join t2 on t1.id = t2.id;

left join

select * from t1 left join t2 on t1.id = t2.id;

right join

right join能轉(zhuǎn)化為left join，例如：

select * from t1 right join t2 on t1.id = t2.id;

能轉(zhuǎn)化為

select * from t2 left join t1 on t1.id = t2.id;

只是前表發(fā)生了變化而已。

大伙可結(jié)合自己的業(yè)務(wù)場(chǎng)景，選擇正確的join。