following is my query:-
ALTER PROCEDURE [dbo].[usp_purchase_order_getid]
-- Add the parameters for the stored procedure here
@bid int
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;
-- Insert statements for procedure here
SELECT ISNULL( MAX(IN_ID+1),1) as id FROM PURCHASE_ORDER
where BRANCH_ID=@bid
END