关于查询 急~~~~~

select * from tb a where not exists

(select 1 from tb where code = a.code and st_date > a.st_date)

select * from 表名 a where not exists(select * from 表名 whree code=a.code and st_date>a.st_date)

declare @t table(code varchar(6),st_date datetime,[name] varchar(4),tsl numeric(12,2))

insert @t select '1001','2003-12-31','kkk',0.04   

insert @t select '1001','2005-12-10','kkk',0.03   

insert @t select '1001','2006-12-1','kkk',0.03   

insert @t select '10030','2004-1-1','ccc',0.03   

insert @t select '10030','2005-1-12','ccc',0.02   

insert @t select '1002','2004-1-10','zzz',0.01 





select *

from @t a

where not exists(select 1 from @t where code = a.code and st_date > a.st_date)

/*





code   st_date                                                name tsl            

------ ------------------------------------------------------ ---- -------------- 

1001   2006-12-01 00:00:00.000                                kkk  .03

10030  2005-01-12 00:00:00.000                                ccc  .02

1002   2004-01-10 00:00:00.000                                zzz  .01



（所影响的行数为 3 行）



*/

create table tb

(

   code int,

   st_date datetime,

   name varchar(10),

   tsl decimal(10,2)

)

insert tb select 1001,   '2003-12-31'   ,'kkk',   0.04   

insert tb select 1001 ,  '2005-12-10'   ,'kkk' ,  0.03   

insert tb select 1001  , '2006-12-1'   ,'kkk'   ,0.03   

insert tb select 10030  , '2004-1-1'  , 'ccc'   ,0.03   

insert tb select 10030   ,'2005-1-12',   'ccc'   ,0.02   

insert tb select 1002   ,'2004-1-10',   'zzz'   ,0.01



select code,min(st_date) st_date,name,cast(min(tsl) as varchar) tsl 

from tb 

group by code,name

order by tsl desc



drop table tb



/*

code        st_date                    name       tsl                            

----------- ------------------------- ---------- ------------------------------ 

1001        2003-12-31 00:00:00.000      kkk        0.03

10030       2004-01-01 00:00:00.000      ccc        0.02

1002        2004-01-10 00:00:00.000      zzz        0.01



（所影响的行数为 3 行）

*/

select *

from table a

where not exists(select 1 from table where code = a.code and st_date < a.st_date)