网上有许多left join ,right join ,inner join的知识,下面只是举例做下:
首先建两个表作为基础.
Code
CREATE TABLE [dbo].[TableA](
[Aa] [nchar](10) NULL,
[Ab] [nchar](10) NULL
) ON [PRIMARY]
CREATE TABLE [dbo].[TableB](
[Aa] [nchar](10) NULL,
[Ab] [nchar](10) NULL
) ON [PRIMARY]
有着表后,当然是加入数据,才能进行测试
Code
insert into TableA
select
'a','1'
union select
'b','2'
union select
'c','3'
union select
'd','4'
union select
'e','5'
union select
'b','6'
union select
'f','7'
insert into TableB
select
'a','1'
union select
'b','2'
union select
'c','3'
union select
'd','4'
union select
'e','5'
union select
'c','6'
union select
'g','7'
然后
select * from tablea left join tableb on aa=ba
select * from tablea right join tableb on aa=ba
select * from tablea inner join tableb on aa=ba
select * from tablea,tableb where aa=ba
这样就可能知道,left ,right,inner 等的用法.