public void getVehicle(AddItem ad = null, UpDe ud = null, AddCustomer adc = null, EditCust edc = null, string veh = null) { String cmd = "exec getVehicle ''"; if (veh != null) { cmd = "exec getVehicle '" + veh + "'"; } using (Conn = new SqlConnection()) { try { Conn.ConnectionString = "Server = (local);Database = Spare_parts;Trusted_Connection = true"; SqlCommand Cmd = new SqlCommand(cmd, Conn); Conn.Open(); SqlDataReader reader = Cmd.ExecuteReader(); if (ad != null) { while (reader.Read()) { ad.Veh(reader[0].ToString()); } } else if (ud != null) { while (reader.Read()) { ud.Veh(reader[0].ToString()); } } else if (edc != null) { while (reader.Read()) { edc.Veh(reader[0].ToString()); } } else { while (reader.Read()) { adc.Veh(reader[0].ToString()); } } } catch (SqlException) { MessageBox.Show("An error occured", "Error"); } } Conn.Close(); }