a表:
yhid(主)
1
2
3
b表:
yhid,s,d
1 s1,s2
1 s2,s3
2 s1,s2
c表:
yhid,s,d,
1 d1,d2
a表与b,c表都是1对多的关系,b表有的yhid,c表不一定有,同样,c表有的yhid,b表不一定有
给a表一个查询条件,希望得到
yhid,s,d
1 s1,s2
1 s2,s3
1 d1,d2
yhid(主)
1
2
3
b表:
yhid,s,d
1 s1,s2
1 s2,s3
2 s1,s2
c表:
yhid,s,d,
1 d1,d2
a表与b,c表都是1对多的关系,b表有的yhid,c表不一定有,同样,c表有的yhid,b表不一定有
给a表一个查询条件,希望得到
yhid,s,d
1 s1,s2
1 s2,s3
1 d1,d2
union
select * from c where yhid in ((select yhid from b) intersect (select yhid from c))
union
select * from c where yhid in(select yhid from b union select yhid from c)
union
select c.yhid,c.s,c.d from a join c on a.yhid=c.yhid where a.yhid=1
select *
from (select b.* from b union select c.* from c) q join a on a.yhid=q.yhid
where a.yhid=1
from (select b.* from b union select c.* from c) q join a on a.yhid=q.yhid
where a.yhid=1