2022-10-31
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mysql学习13-横向连接查询
-- 24 横向连接查询 (多表连接查询)
create table t1(sname char,sid int);
create table t2(sname char,score int);
insert into t1 values('a',1),('b',3),('c',4),('d',9),('f',8);
insert into t2 values('a',90),('b',91),('c',82),('d',83),('e',84);
select * from t1;
select * from t2;
##表连接
-- 1,左连接
select * from t1
left join t2
on t1.sname=t2.sname;
-- 2,右连接
select * from t1
right join t2
on t1.sname=t2.sname;
-- 3,内连接
select * from t1 inner join t2 on t1.sname=t2.sname;
-- 4,交叉连接
select * from t1,t2;
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