select B.name1,C.name2 from A,B,C where A.id1=B.id1 and A.id2=C.id2
-- 1, 内连接 select B.name1, C.name2 from A,B,C where A.id1=B.id1 and A.id2=B.id2-- 2 子查询 select (select name1 from B where B.id1=A.id1) name1, select name2 from C where C.id2=A.id1) name2 from A;
-- 1, 内连接 select B.name1, C.name2 from A,B,C where A.id1=B.id1 and A.id2=C.id2-- 2 子查询 select (select name1 from B where B.id1=A.id1) name1, select name2 from C where C.id2=A.id1) name2 from A;
select b.name1,c.name2 from A inner join B on a.id1=b.id1 inner join C on a.id2=c.id2这个应该是比较常见通用的方法了。
如果组合起来,不至少50种。供先的组合有 inner join, left jion, where a.id=b.id, using(id), select (select name from b where id=a.id), 等等!
select name1, name2 from A left join B on A.id1=B.id1 left join C on A.id2 on C.id2
from A,B,C
where A.id1=B.id1 and A.id2=C.id2
-- 1, 内连接
select B.name1, C.name2
from A,B,C
where A.id1=B.id1
and A.id2=B.id2-- 2 子查询
select (select name1 from B where B.id1=A.id1) name1,
select name2 from C where C.id2=A.id1) name2
from A;
select B.name1, C.name2
from A,B,C
where A.id1=B.id1
and A.id2=C.id2-- 2 子查询
select (select name1 from B where B.id1=A.id1) name1,
select name2 from C where C.id2=A.id1) name2
from A;
from A inner join B on a.id1=b.id1
inner join C on a.id2=c.id2这个应该是比较常见通用的方法了。
inner join, left jion, where a.id=b.id, using(id), select (select name from b where id=a.id), 等等!
select name1, name2 from A left join B on A.id1=B.id1 left join C on A.id2 on C.id2