else if (evt.getSource() == addNewEntryButton) {
		if ( con == null ) {
			Print("Not connected.");
			return;
		}
		
		try {
			boolean dataIsValid = true;
			java.sql.Date deadlineOfDelivery = null;
			
			if (idField.getText().length() != 0 ) { // if ID field is filled, it has to be filled with an integer.
				try { Integer.parseInt(idField.getText()); }
				catch (NumberFormatException n) { 
					result.append("The ID field must contain an integer.\n"); 
					dataIsValid = false; 
				}
			}
			
			if ( dataIsValid ) {		//vehicle type must be g/c/d/v/l/a
				if ( 	!vehicleType.getText().equals("g")
						&& !vehicleType.getText().equals("c")
						&& !vehicleType.getText().equals("d")
						&& !vehicleType.getText().equals("v")
						&& !vehicleType.getText().equals("l")
						&& !vehicleType.getText().equals("a") ) {
						result.append("The vehicle type must be either g, c, d, v, l or a.\n");
						dataIsValid = false;
				}
			}
			
			if ( dataIsValid ) {		//quantity must be an integer
				try { Integer.parseInt(quantity.getText()); }
				catch (NumberFormatException n) { 
					result.append("The quantity field must contain an integer.\n");
					dataIsValid = false;
				}
			}
					
			if ( dataIsValid ) {		// date check
				dataIsValid = ( deadline.getText().matches("[0-9]{12}") || deadline.getText().length() == 0 ); 
				if (!dataIsValid) result.append("The input string is not using the valid date format.");
			}
			
			if ( dataIsValid ) {		// if a date was given, its format is checked
				if (deadline.getText().length() != 0) {
					try {
						SimpleDateFormat formatter = new SimpleDateFormat("yyyyMMddHHmm");
						formatter.setLenient(false);
						deadlineOfDelivery 			= new java.sql.Date(formatter.parse(deadline.getText()).getTime());
					}
					catch (ParseException e) {
						result.append("The date format is invalid.\n");
						dataIsValid = false;
					}
				}
			}
			
			if ( dataIsValid ) {		// description, origin and destination check
				dataIsValid = !( origin.getText().length() == 0 || destination.getText().length() == 0 || description.getText().length() == 0 );
				if ( !dataIsValid ) result.append("You cannot leave neither the description, the origin nor destination fields empty.\n");
			}
			
			if ( dataIsValid ) {
				int vehicleID 				= Integer.parseInt(idField.getText());
				String descr 				= description.getText();
				String typeOfVehicle		= vehicleType.getText();
				int quantityOfOrder			= Integer.parseInt(quantity.getText());
				String whereItComesFrom		= origin.getText();
				String whereItGoesTo		= destination.getText();
				String commentOnDelivery	= comments.getText();
				
				// inserts a completely new entry. used when date and ID were given for the generation.
				PreparedStatement insertNewEntry 	= con.prepareStatement("INSERT INTO orders (id, description, vehicle_type, quantity, origin, destination, " + 
				"deadline, comments) VALUES ( ?, ?, ?, ?, ?, ?, ?, ?)");
				
				// updates an old entry. used when date was given.
				PreparedStatement updateOldEntry 	= con.prepareStatement("UPDATE orders SET description = ?, vehicle_type = ?," +
				 "quantity = ?, origin = ?, destination = ?, deadline = ?, comments = ? WHERE id = ?");
				 
				// inserts a completely new entry. used when only date was given.
				PreparedStatement insertNewID		= con.prepareStatement("INSERT INTO orders (id, description, vehicle_type, quantity, origin, destination, " + 
				"deadline, comments) VALUES ( sequence_1.nextval, ?, ?, ?, ?, ?, ?, ?)");
				
				// inserts a new entry. used when only ID was given.
				PreparedStatement insertDefDate		= con.prepareStatement("INSERT INTO orders (id, description, vehicle_type, quantity, origin, destination, " +
				"comments) VALUES (?, ?, ?, ?, ?, ?, ?)");
				
				// updates an entry. used when no date was given.
				PreparedStatement updateDefDate		= con.prepareStatement("UPDATE orders SET description = ?, vehicle_type = ?," +
				 "quantity = ?, origin = ?, destination = ?, deadline = default, comments = ? WHERE id = ?");
				 
				 // inserts a new entry. used when neither date nor ID was given.
				PreparedStatement insertDefDateID	= con.prepareStatement("INSERT INTO orders (id, description, vehicle_type, quantity, origin, destination, " + 
				"comments) VALUES ( sequence_1.nextval, ?, ?, ?, ?, ?, ?)");
				
				if ( deadline.getText().length() == 0 ) {			// date should be default
					if ( idField.getText().length() == 0 ) { 		// id should be default
						insertDefDateID.setString(1, descr);
						insertDefDateID.setString(2, typeOfVehicle);
						insertDefDateID.setInt(3, quantityOfOrder);
						insertDefDateID.setString(4, whereItComesFrom);
						insertDefDateID.setString(5, whereItGoesTo);
						insertDefDateID.setString(6, commentOnDelivery);
						insertDefDate.execute();
						result.append("The entry has been succesfully added with a newly generated ID and default date settings.\n");
					}

					else {											// an ID was given
						Statement searchForID = con.createStatement();
						ResultSet rs = searchForID.executeQuery("SELECT * FROM orders WHERE id = " + vehicleID);
				
						if (rs.next()) { 							// found old entry, updating
							updateDefDate.setString(1, descr);
							updateDefDate.setString(2, typeOfVehicle);
							updateDefDate.setInt(3, quantityOfOrder);
							updateDefDate.setString(4, whereItComesFrom);
							updateDefDate.setString(5, whereItGoesTo);
							updateDefDate.setString(6, commentOnDelivery);
							updateDefDate.setInt(7, vehicleID);
							updateDefDate.executeUpdate();
							result.append("The entry with ID " + vehicleID + " has been successfully updated using default date settings.\n");
						}
				
						else {										// new entry with ID given and default date
							insertDefDate.setInt(1, vehicleID);
							insertDefDate.setString(2, descr);
							insertDefDate.setString(3, typeOfVehicle);
							insertDefDate.setInt(4, quantityOfOrder);
							insertDefDate.setString(5, whereItComesFrom);
							insertDefDate.setString(6, whereItGoesTo);
							insertDefDate.setString(7, commentOnDelivery);
							insertDefDate.execute();
							result.append("The entry with ID " + vehicleID + " and default date settingshas been successfully added.\n");
						}
					}
				}
				
				else {												// a date was given
					if ( idField.getText().length() == 0 ) { 		//there was no id input, so a new id is given and the entry is made
						insertNewID.setString(1, descr);
						insertNewID.setString(2, typeOfVehicle);
						insertNewID.setInt(3, quantityOfOrder);
						insertNewID.setString(4, whereItComesFrom);
						insertNewID.setString(5, whereItGoesTo);
						insertNewID.setDate(6, deadlineOfDelivery);
						insertNewID.setString(7, commentOnDelivery);
						insertNewID.execute();
						result.append("The entry has been succesfully added with a newly generated ID.\n");
					}

					else {											// if an ID was given, it may update or create a row
						Statement searchForID = con.createStatement();
						ResultSet rs = searchForID.executeQuery("SELECT * FROM orders WHERE id = " + vehicleID);
				
						if (rs.next()) { 							// there was a line with such id, it is updated with a given date
							updateOldEntry.setString(1, descr);
							updateOldEntry.setString(2, typeOfVehicle);
							updateOldEntry.setInt(3, quantityOfOrder);
							updateOldEntry.setString(4, whereItComesFrom);
							updateOldEntry.setString(5, whereItGoesTo);
							updateOldEntry.setDate(6, deadlineOfDelivery);
							updateOldEntry.setString(7, commentOnDelivery);
							updateOldEntry.setInt(8, vehicleID);
							updateOldEntry.executeUpdate();
							result.append("The entry with ID " + vehicleID + " has been successfully updated.\n");
						}
				
						else {										// new entry with given date and ID
							insertNewEntry.setInt(1, vehicleID);
							insertNewEntry.setString(2, descr);
							insertNewEntry.setString(3, typeOfVehicle);
							insertNewEntry.setInt(4, quantityOfOrder);
							insertNewEntry.setString(5, whereItComesFrom);
							insertNewEntry.setString(6, whereItGoesTo);
							insertNewEntry.setDate(7, deadlineOfDelivery);
							insertNewEntry.setString(8, commentOnDelivery);
							insertNewEntry.execute();
							result.append("The entry with ID " + vehicleID + " has been successfully added.\n");
						}
					}
				}
			}
		}
		catch (SQLException e) { result.append(e.toString()); }
	}