问检查表中是否存在所有年份的存储过程

EN

ALTER PROCEDURE [dbo].[CheckExistenceforyear] 

    @StYear int  = 0, 
    @EdYear int = 0,
    @SubStationID int = 0,
    @YrString varchar(255) = null Output
AS
BEGIN   
SET NOCOUNT ON;    

    Declare @TempValue varchar(4)
    if @StYear <= @EdYear
    while @StYear <= @EdYear
    Begin
    if (select Count(Sub.Year) from table sub where Sub.Year=@StYear and Sub.SubStationID = @SubStationID) > 0
            Begin

            select  @TempValue=Sub.Year from table as sub where Sub.Year=@StYear and Sub.SubStationID = @SubStationID
                set @YrString = @YrString + @TempValue  
            End
            set @StYear = @StYear +1  
        End
    Else
        return -1 

    select @YrString    
END