public static EquipmentList Retrieve(cInvoice invoice) { EquipmentList list = new EquipmentList(invoice); List <ParamStruct> paramiters = new List <ParamStruct>(); paramiters.Add(new ParamStruct("@invoiceId", invoice.InvioceNum, System.Data.DbType.Int32, 4, System.Data.ParameterDirection.Input)); DbDataReader reader = DAL.DAL.ReadData("retrieveInvoiceData", paramiters); while (reader.Read()) { cEquipment equip = cEquipmentSQL.RetrieveEquipment(Convert.ToInt32(reader["equipmentId"])); list.AddEquipment(equip); } return(list); }