Depending On The Selection Of The User Of The Asp.net Web-form How Can I Do Changes In The Stored Procedure

Hi frdz,  I have created the following stored procedure in sql server 2005. In my database i have one option for the payment mode which can be done thru cash or credit(cheque).   I have created my web-application in asp.net with C# 2005. There i have a dropdownlist box for the user to select the option whether wants to do the payment thru cash or cheque.Depending on that selection if user selects cheque then all the reqt for cheque like it's no,dt,bankname etc...are visible.but if user selects the option as cash then the cheque details become invisible.Depending on the selection of the user of the asp.net web-form how can i do changes in the stored procedure...   i can write the condition likeif paymentmode=cash then ..........else.............but where and how can it be written ...pls tell methanxs in adv...u can go thru my below SP     ALTER PROCEDURE MiscellaneousStoredProcedure


@miscid int output,
@storename varchar(20),--store name to storeid
@accountname varchar(20),
@groupname varchar(20),
@paymentdt datetime,
@payeename varchar(30),
@paymode varchar(20),
@bankname varchar(50),
@chqdt datetime,
@chqno varchar(20),
@amt numeric(10, 2),
@bal numeric(10, 2),
@remarks varchar(50)

as

declare

@storeid int,
@accountid int,
@groupid int



begin
set nocount on
select @miscid = isnull(max(@miscid),0) + 1 from miscellaneourpay

if exists (select * from storemaster where storename = @storename)
select @storeid = storeid from storemaster where storename = @storename

if exists (select * from accountmaster where accountname =@accountname)
select @accountid = accountid from accountmaster where accountname =@accountname

if exists (select * from accountgroupmaster where groupname=@groupname)
select @groupid=groupid from accountgroupmaster where groupname=@groupname




begin transaction
insert into miscellaneourpay
(
miscid,
storeid,
accountid,
groupid,
paymentdt,
paymode,
payeename,
bankname,
chqdt,
chqno,
amt,
bal,
remarks

)
values
(

@miscid,
@storeid,
@accountid,
@groupid,
@paymentdt,
@paymode,
@payeename,
@bankname,
@chqdt,
@chqno,
@amt,
@bal,
@remarks

)
commit transaction

end