select * from tablename t where 主键字段=
(
select max(主键字段) from tablename 
where ProductID=t.ProductID and GuiGe=t.GuiGe and XingHao=t.XingHao and SalePrice=t.SalePrice
)

------解决方案--------------------
SQL code


--方法一：
select distinct ProductID,GuiGe,XingHao,SalePrice into  temp from tb 

truncate table tb

insert into( ProductID,GuiGe,XingHao,SalePrice) 
 select  ProductID,GuiGe,XingHao,SalePrice
   from temp