SQL语句高手请进！跪求帮助！

[liulinguang]

现在有两张表：Members表和Virtual表
这两张表中都有身份证字段，Members中是_id，Virtual中是_vid
有这么一个需求：
查出Members表中的所有数据，并且每条数据在输出的时候多显示一列，这一列标识该条数据中的_id与Virtual表中的_vid是否重复，也就是_id的值在表Virtual表中是否同时存在！

[AcHerat]

select *,
  (case when exists(select 1 from Virtual where [_vid] = t.[_id]) then 1 else 0 end) tFlag
from Members t

[快溜]

select *,(case when exists(select 1 from Virtual where [_vid] = t.[_id]) then 1 else 0 end) flag
from Members t

[-晴天]

select a.*,(case when b._vid is not null then 1 else 0 end)flg
from members a left join(
select distinct _vid from Virtual)b on a._id=b._vid

[Felixzhaowenzhong]

楼上均为正解

[dawugui]

select m.* , '存在' from Members m , Virtual n where m._id = n._vid
union all
select m.* , '不存在' from Members m where not exists(select 1 from Virtual n where m._id = n._vid)

select m.* , '存在' from Members m , Virtual n where m._id = n._vid
union all
select m.* , '不存在' from Members m where _id not in (select _vid from Virtual n)

[中国风]

select a._id,max(case when b._vid is null then 0 else 1 end)flg
from members a 
left join Virtual as b on a._id=b._vi
group by a._id

[dawugui]

[code=SQL]select m.* , '存在' from Members m where exists(select 1 from Virtual n where m._id = n._vid)
union all
select m.* , '不存在' from Members m where not exists(select 1 from Virtual n where m._id = n._vid)

select m.* , '存在' from Members m , Virtual n where m._id = n._vid
union all
select m.* , '不存在' from Members m where not exists(select 1 from Virtual n where m._id = n._vid)

select m.* , '存在' from Members m , Virtual n where m._id = n._vid
union all
select m.* , '不存在' from Members m where _id not in (select _vid from Virtual n)

[/code]

[我想静静0v0]

select *,
iscf_id=(case when exists(select 1 from Virtual v where m.id=v.vid) then 1 else 0 end)
from Members m

[--小F--]

select
 *,(case when exists(select 1 from Virtual where [_vid] = t.[_id]) then 1 else 0 end) as flag
from
 Members t