i have this Proc

CREATE Proc [dbo].Salse_Ditail
-- Add the parameters for the stored procedure here @Report_Form varchar(1) , @DateFrom datetime , @DateTo datetime , @COMPANYID varchar(3), @All varchar(1) , @All1 varchar(1) ,
@All2 varchar(1) ,
@All3 varchar(1) , @All4 varchar(1) ,
@All5 varchar(1) ,
@Sector varchar(10), @Report_Parameter nvarchar(max)
as BEGIN -- SET NOCOUNT ON added to prevent extra result sets from -- interfering with SELECT statements. DECLARE @STRWhere nvarchar(max)

IF @All5=0 AND @All4=0 AND @All3=0 AND @All2=0 AND @All1=0 and @All=1 
    set @STRWhere=  N'and  Sector_id = @Sector'  

if @Report_Form =1 or @Report_Form =3 or @Report_Form =4  

SELECT   RETURNREASONCODEID, SITE,SITE_NAME,Factory_id,Factory_Name,Sector_id,sector_name,Customer_name, 
     Customer_id,ITEMID,ITEMNAME,SALESMANID,SALESMAN_NAME,Net_Qty,Net_Salse,Gross_Sales,Gross_Qty, 
     NETWEIGHT_Gross,NETWEIGHT_salse_Gross,NETWEIGHT_NET,NETWEIGHT_salse_NET,Return_Sales,Free_Good, 
     CollectionAmount   

FROM hal_bas_new_rep  

WHERE   DATAAREAID =@COMPANYID AND INVOICEDATE >= @DateFrom  
    AND INVOICEDATE <= @DateTo and Report_Activti = @Report_Form  

if  @Report_Form =2   

    SELECT   RETURNREASONCODEID ,  RETURNREASONDESC,  SITE , SITE_NAME , Factory_id , 
        Factory_Name ,  Sector_id ,  sector_name ,  Customer_name ,  Customer_id ,  
        ITEMID , ITEMNAME , SALESMANID , SALESMAN_NAME ,    Return_Sales    

    FROM dbo.hal_bas_new_rep  

    WHERE  DATAAREAID =@COMPANYID AND INVOICEDATE >= @DateFrom  
        AND INVOICEDATE <= @DateTo and Report_Activti =   @Report_Form  
        and  RETURNREASONCODEID in 
        ( 
            SELECT     Val  
            FROM dbo.fn_String_To_Table(@Report_Parameter,',',1) 
        )   
        /* 
        @STRWhere   question how i can but the virble here   
        */ 

end GO i want to but virble put a variable under where Expression and from this function buc I have many function i want to add

if any one have answer pls send me