存储过程之日周月统计

CREATE proc  energy_data
@id int
as
begin
  declare @maxDL decimal ,  @minDayDL decimal, @minWeekDL decimal , @minMonthDL decimal,@DayDL  decimal
  -- get the maxDL
  select @maxDL = max(convert(decimal,dianliang)) from data where datatime >= convert(nvarchar(20),getdate(),101) and id=@id
  --get the minDayDL
  select @minDayDL = min(dianliang) from data where datatime>convert(nvarchar(20),getdate(),101) and id=@id
  --get the minWeekDL 
  select @minWeekDL = min(dianliang) from data  where datatime>convert(nvarchar(20),dateadd(day,-7,getdate()),101) and id=@id
  --get the minMonthDL
  select @minMonthDL = min(dianliang) from data  where datatime>convert(nvarchar(20),dateadd(day,-30,getdate()),101) and id=@id
 
     begin
         set  @DayDL=@maxDL -@minDayDL
          
          if  @maxDL=null
                 begin
                   select @maxDL=max(convert(decimal,dianliang))   from data where id=@id
                   set @DayDL=0
                end
              select  @DayDL as DayDL,  @maxDL - @minWeekDL as WeekDL,@maxDL - @minMonthDL as MonthDL
       end   
  
end
GO
功能：

查询 统计日，周，月的数据