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表a 表b 表c
id id id
b_id name b_id
message message
create view Test
as
select a.id as mid,a.b_id as mbid,a.message as mmessage,b.name as mname from a,b where a.id=b.id
union all
select c.id as mid,c.b_id as mbid,c.message as mmessage,b.name as mname from b,c where b.id=c.id
select a.id as mid,a.b_id as mbid,a.message as mmessage,b.name as mname from a,b where a.id=b.id
union all
select c.id as mid,c.b_id as mbid,c.message as mmessage,b.name as mname from b,c where b.id=c.id
这样试试select a.id,b.b_id,b.name,a.message from 表a as a inner join 表b as b on a.b_id=b.id
select c.id,b.b_id,b.name,c.message from 表c as c inner join 表b as b on c.b_id=b.id
(1)select a.*,b.* from a,b where a.id=b.id
(2)select b.*,c.* from b,c where b.id=c.id