public void complexDiscount(string discountArray, int storeID, string type, double percentage, string duration, int sessionID) { if (storeID < 0) { throw new ILLArgumentException("illegal store number"); } if (sessionID < 0) { throw new NullReferenceException("session is a null reference"); } db.complexDiscount(discountArray, storeID, type, percentage, duration, sessionID); }