--竖表变横表，交叉表查询算法

use pubs

GO

--建立测试表

create table TESTA(A varchar(20),B varchar(20),QTY int)

insert into TESTA

    select 'A1','B1',2 union

    select 'A2','B2',5 union

    select 'A3','B1',4 union

    select 'A1','B2',6

--显示竖表

select * from TESTA

--显示横表

declare @sql nvarchar(1000)

select @sql=''

select @sql=@sql+',['+B+']=max(case B when '''+B+''' then QTY else 0 end)'

    from TESTA

    group by B

print 'select A'+@sql+' from TESTA group by A'

exec('select A'+@sql+' from TESTA group by A')

--删除测试表

drop table TESTA