mysql中几种连接的写法_CDA答疑社区

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wo56565

2020-02-19 阅读量: 855

mysql中几种连接的写法

-- 左连接
select *
from t1 left join t2 on key1=key2;

-- 右连接
select *
from t1 right join t2 on key1=key2;

-- 左反连接
select *
from t1 left join t2 on key1=key2

where key2 is null;

-- 右反连接
select *
from t1 right join t2 on key1=key2
where key1 is null;
-- 纵向合并

select * from t1

union

select * from t2;

select * from t1

union all

select * from t2;

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