请教一个SQL语句，希望大家帮忙！

[yshuui]

有这样一个数据库表格

字段1 字段2 字段3 字段4 字段5 字段6
1 2 a a1 b b1
2 3 c c1 a a2

想得到‘字段3’或者‘字段5’=a的记录
字段4和字段3，字段6和字段5是相关的，一起查出来。

要查询的结果为
字段1 字段2 字段3 字段4
1 2 a a1
2 3 a a2

请教用sql怎么做查询？

[ojuju10]

create table aa(c1 int,c2 int,c3 varchar(10),c4 varchar(10),c5 varchar(10),c6 varchar(10))
insert into aa select 1,     2,    'a',    'a1',    'b',     'b1' 
insert into aa select 2,     3,    'c',    'c1',    'a',     'a2' 

select c1,c2,c3,c4 from aa a
where c3='a'
union all
select c1,c2,c5,c6 from aa a
where c5='a'

[zhou968]

create table tb(col1 int,col2 int,col3 varchar(10),col4 varchar(10),col5 varchar(10),col6 varchar(10))
insert into tb select 1,2,'a','a1','b','b1' union all select 2,3,'c','c1','a','a2'

select col1,col2,col3,col4 from tb where col3 = 'a'
union all 
select col1,col2,col5,col6 from tb where col5='a'

[swot2008]

[code=SQL]select 字段1,字段2,字段3,字段4 
from tab 
where 字段3 ='a' or 字段5='a'

[/code]

[swot2008]

select 字段1,字段2,字段3,字段4 
from tab 
where 字段3 ='a' or 字段5='a'

[qys2000]

select * from tb where 字段3 ='a' or 字段5='a'

[yshuui]

谢谢大家，已经解决。

[yshuui]

select 字段1 字段2 字段3 字段4 from table where 字段3='a'
union
select 字段1 字段2 字段5 字段6 from table where 字段5='a'

[jinjazz]

select * from tb where 字段3 ='a' or 字段5='a'

[pt1314917]

字段1 字段2 字段3 字段4
1 2 a a1
2 3 a a2

红色部分的结果是怎么来的？

[lff642]

--try
create table tb(col1 int,col2 int,col3 varchar(10),col4 varchar(10),col5 varchar(10),col6 varchar(10))
insert into tb select 1,2,'a','a1','b','b1' union all select 2,3,'c','c1','a','a2'

select col1,col2,col3,col4 from tb where col3 = 'a'
union all 
select col1,col2,col5,col6 from tb where col5='a'

drop table tb

[lff642]

---result
/*
col1   col2     col3    col4
1	2	a	a1
2	3	a	a2

*/

[zanyzyg]

借用一下

create table tb(col1 int,col2 int,col3 varchar(10),col4 varchar(10),col5 varchar(10),col6 varchar(10))
insert into tb select 1,2,'a','a1','b','b1' union all select 2,3,'c','c1','a','a2'

select col1,col2,case when col3='a' then col3 else col5 end as col3,case when col3='a' then col4 else col6 end as col4 from tb

drop table tb

[zanyzyg]

不好意思，少了where部分

借用一下

create table tb(col1 int,col2 int,col3 varchar(10),col4 varchar(10),col5 varchar(10),col6 varchar(10))
insert into tb select 1,2,'a','a1','b','b1' union all select 2,3,'c','c1','a','a2'

select col1,col2,case when col3='a' then col3 else col5 end as col3,case when col3='a' then col4 else col6 end as col4 from tb where col3='1' or col5='a'

drop table tb