select table1.name,table2.name,table3.name from table1,table2,table3 where table1.id=table2.id
--group by table1.name --我的目的是table1,table2中相同的名字
只显示一个,请问我这group by加到哪最合适呢?
-- 这个是要加的子查询
and table2.BID=table3.BID
--group by table1.name --我的目的是table1,table2中相同的名字
只显示一个,请问我这group by加到哪最合适呢?
-- 这个是要加的子查询
and table2.BID=table3.BID
from table1,table2,table3 where table1.id=table2.id group by table1.name 这样是可以去掉相同的NAME
但是3张表连接查询的时候怎么写呢?select table1.name,table2.name,table3.name from table1,table2,table3 where table1.id=table2.id group by table1.name and table2.BID=table3.BID???请问这儿语句怎么改写呢?
union all
(
select name from table1
union
select name from table2
) t
union all
select name from
(
select name from table1
union
select name from table2
) t
from table1,table2,table3 where table1.id=table2.id
group by table1.name ,table2.name ,table3.name
from table1 left join table2 on table1.id=table2.id
left join table3 on table2.BID=table3.BID
group by table1.name,table2.name,table3.name
from table1 inner join table2 on table1.id=table2.id --inner join
inner join table3 on table2.BID=table3.BID
group by table1.name,table2.name,table3.name