add delete option and error handling to tours

lib/db/tour.vala

@@ -129,6 +129,29 @@ namespace LibSernatur {
 					#endif
 				}
 			}
+
+			/**
+			 * Delete a tour in the database
+			 * @param conn The database connection
+			 * @param tour The tour to update
+			 * @throws DBError Thrown if the data in the object is invalid
+			 */
+			public static void delete_tour (Database conn, Tour tour) throws DBError {
+				if (tour.id_tour == 0) {
+					throw new DBError.INVALID_VALUE (dgettext (null, "The id of the tour is invalid!"));
+				}
+				var res = conn.exec (Query.get_query (Query.Type.DELETE_TOUR, tour));
+				if (res.get_status () != ExecStatus.COMMAND_OK) {
+					if (res.get_error_field (FieldCode.SQLSTATE) == "23503") {
+						throw new DBError.FOREIGN_KEY_CONSTAINT (res.get_error_field (FieldCode.MESSAGE_PRIMARY));
+					}
+					#if DEBUG
+						error (conn.get_error_message ());
+					#else
+						warning (conn.get_error_message ());
+					#endif
+				}
+			}
 		}
 	}
 }