这个查询语句那里不对了?

[网络科技]

select * from table1 a,table2 b,table3 c where a.userid='xzy' or b.userid='xzy' or c.userid='xzy'

说明:我要在三个表中,查询看是否有userid值为"xzy"的记录,只要有任意一个表中userid值为"xzy",就算找到记录,
以上写法好像不行,我table1表中有userid值为"xzy"的记录,可查询结果还是为空,为什么呢?感觉这个也很简单,没想到写了查不到,请大虾们帮忙看下吧,谢了!

[htl258_Tony]

like '%xzy%'

可能存在的内容不够精确吧.换用LIKE的试试.

[子陌红尘]

select 
    * 
from 
    table1 a
full outer join
    table2 b
full outer join
    table3 c 
where
    isnull(a.userid,'')='xzy' or isnull(b.userid,'')='xzy' or isnull(c.userid,'')='xzy'

[feixianxxx]

select * from table1 a
where a.userid='xzy'
union all
select * from table2 b
where  b.userid='xzy' 
union all
select * from table3 c 
c.userid='xzy'

用union all 代替 OR 这样效率也高

[dj3688]

顶钻钻~~

[feixianxxx]

select * from table1 a
where a.userid='xzy'
union all
select * from table2 b
where  b.userid='xzy' 
union all
select * from table3 c 
where c.userid='xzy'

[子陌红尘]

或许楼主要的是这个效果：

select * from table1 where userid='xzy'
union all
select * from table2 where userid='xzy'
union all
select * from table3 where userid='xzy'

[上善若水_厚德载物]

if object_id('table1') is not null
  drop table table1
create table table1
(
  userid varchar(10)
)

if object_id('table2') is not null
  drop table table2
create table table2
(
  userid varchar(10)
)

if object_id('table3') is not null
  drop table table3
create table table3
(
  userid varchar(10)
)

insert table1
select 'xzy'

insert table2
select 'abc'

insert table3
select 'ccc'


select * from table1 a,table2 b,table3 c where a.userid='xzy' or b.userid='xzy' or c.userid='xzy'

/**
userid     userid     userid     
---------- ---------- ---------- 
xzy        abc        ccc

（所影响的行数为 1 行）
**/

[网络科技]

各位速度快啊,解决了,感谢各位帮忙,结了!