怎么使用Min()函数

如何使用Min()函数?
比如有如下数据:
ItemID ToolModulePmTypeSetDate T TFlag
201100201014DWPRS07@AllModuleW_P2011-11-287AY
201100201015DWPRS07@AllModuleW_P2011-12-5 7AY
201100201016DWPRS07@AllModuleW_P2011-12-127AY
201100201017DWPRS07@AllModuleW_P2011-12-197AY
201100201018DWPRS07@AllModuleW_P2011-12-267AY
201200201001DWPRS07@AllModuleM_P2012-1-2 7AY
201100212001DWPRS07@AllModuleM_P2011-8-29 30AY
201100212002DWPRS07@AllModuleM_P2011-9-28 30AY
201100212003DWPRS07@AllModuleQ_P2011-10-2830AY
201100212004DWPRS07@AllModuleQ_P2011-11-2730AY

通过 搜索语句搜索到:
ItemID ToolModulePmTypeSetDate T TFlag
201100201014DWPRS07@AllModuleW_P2011-11-287AY
201200201001DWPRS07@AllModuleM_P2012-1-2 7AY
201100212003DWPRS07@AllModuleQ_P2011-10-2830AY

如何写这个语句呢...
(PmType为不同的，SetDate取 最小日期的数据，)


[解决办法]

SQL code

select * from tb a where not exists(select 1 from tb where PmType=a.PmType and SetDate<a.SetDate)
[解决办法]
SQL code
select ItemID,ToolModule,PmType,T,TFlag,min(SetDate) as SetDatefrom   tablenamegroup by ItemID,ToolModule,PmType,T,TFlag
[解决办法]
探讨

SQL code
select ItemID,ToolModule,PmType,T,TFlag,min(SetDate) as SetDate
from   tablename
group by ItemID,ToolModule,PmType,T,TFlag

[解决办法]
SELECT tablename.* FROM tablename INNER JOIN (select ToolModule,PmType,T,TFlag,min(SetDate) as SetDateA
from   tablename)
group by ToolModule,PmType,T,TFlag) AS A ON  
tablename.ToolModule=A.ToolModule  AND
tablename.PmType=A.PmType AND
tablename.T=A.T AND
tablename.TFlag=A.TFlag AND
tablename.SetDate=A.SetDateA
  

[解决办法]
SQL code
select a.*   from tb as a     , (select min(SetDate) as MinSetDate,PmType from tb group by PmType) as b where a.PmType=b.PmType   and a.SetDate=b.MinSetDate