MSSQL分组排序耗时问题，小白适用

   declare @a datetime
   set     @a=getdate()
   SELECT Material_Code  FROM  dbo.BAS_Material
   select [语句执行花费时间(毫秒)]=datediff(ms,@a,getdate())
   
   declare @b datetime 
   set     @b=getdate()
   SELECT  Material_Code FROM  dbo.BAS_Material group by Material_Code 
   select [语句执行花费时间(毫秒)]=datediff(ms,@b,getdate())
   
   declare @c datetime
   set     @c=getdate()
   SELECT Material_Code FROM  dbo.BAS_Material order by Material_Code 
   select [语句执行花费时间(毫秒)]=datediff(ms,@c,getdate())

结果显而易见：