ALTER FUNCTION [dbo].[FNA_GET_AVAILABLE_BALANCE_POINTS](@CustomerId BIGINT) RETURNS MONEY AS BEGIN DECLARE @BALANCE MONEY SELECT @BALANCE = ISNULL(SUM(CASE WHEN tranType = 'CR' THEN amount ELSE -1 * amount END), 0) FROM Customer_Promotion CP(NOLOCK) WHERE sourceCustomerId = @CustomerId RETURN ISNULL(@BALANCE, 0) END