表b1
id 1
name a
id 2
name b
id 3
name c表b2
id 1
type aa
id 2
type bb
id 3
type cc表 b3
id 2
name a
id 3
name e想检索:三个表中所有name=a的数据,并且id,name,type要都显示出来
id 1
name a
id 2
name b
id 3
name c表b2
id 1
type aa
id 2
type bb
id 3
type cc表 b3
id 2
name a
id 3
name e想检索:三个表中所有name=a的数据,并且id,name,type要都显示出来
where b1.id=b2.id and b1.name=a
union
select b3.id,b3.name,b2.type from b3,b2
where b3.id=b2.id and b3.name=a
好象会有重复数据
记录如下:
b1 b2 b3
a aa
b bb a
c cc e三个表中以 id 联系 ,表2中没有name字段想检索出
id name type
1 a aa
2 b bb (因为表b3中name=a)
select b1.*,b2.*.b3.* from b1 left join b2 on b1.id=b2.id left join b3 on b2.id=b3.id where b1.name='a'
union all ??能详细点吗,,谢谢了
select * from b1 w,b2 m,b3 n where (w.id=m.id and w.name='a')or(w.id=m.id and w.id=n.id and n.name='a')
union
select a1.id,a1.name,a2.type from b1 a1,b2 a2 where a1.name='a' and a1.id=a2.id