TrackDAO: what can be improved?

In this specific situation there is a table with trackdata and a form to add rows. For the sake of clarity I won't include the view-related code here. The added rows are added to a LinkedList when appropriate.

public class TrackDAO {
private List<Track> tracks;
private Connection con;

public TrackDAO() {
    tracks = new LinkedList<Track>();
}

public void addTrack(Track track){
    tracks.add(track);
}

I use a Singleton class for the Database connection.

public void connect() throws Exception{
    con = Database.getInstance().connect();
}

public void disconnect() {
    Database.getInstance().disconnect();
}

Files can be stored & retrieved locally.

public void saveToFile(File file) throws IOException {
    File getFile = file;
    if (Utils.getExtension(getFile) == null){
        String url = getFile.getAbsolutePath();
        url += "." + Utils.ml;
        getFile = new File(url);
    }

    FileOutputStream fos = new FileOutputStream(getFile);
    ObjectOutputStream oos = new ObjectOutputStream(fos);

    Track[] trackArray = tracks.toArray(new Track[tracks.size()]);
    oos.writeObject(trackArray);
    oos.close();
}

public void loadFromFile(File file) throws IOException {
    FileInputStream fis = new FileInputStream(file);
    ObjectInputStream ois = new ObjectInputStream(fis);
    try {
        Track[] trackArray = (Track[])ois.readObject();
        tracks.clear();
        tracks.addAll(Arrays.asList(trackArray));
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    }
    ois.close();
}

When the table view is being opened the data will load into the table.

    public void loadData() throws SQLException{
    tracks.clear();
    String sql = "select id, artist, title, album, tuning, genre, url from track order by title";
    Statement selectStatement = con.createStatement();
    selectStatement.executeQuery(sql);
    ResultSet results = selectStatement.getResultSet();
        while(results.next()){
            int id = results.getInt("id");
            String artist = results.getString("artist");
            String title = results.getString("title");
            String album = results.getString("album");
            String tuning = results.getString("tuning");
            String genre = results.getString("genre");
            String fileUrl = results.getString("url");

            Track track = new Track(id, artist, title, album, tuning, genre, fileUrl);
            tracks.add(track);
            System.out.println(track);
        }
    results.close();
    selectStatement.close();
}

When the application is being closed the method will query the database for each id and check wether it has to update or insert the track.

public void saveToDatabase()throws SQLException {               
    String checkSql = "select count(*) as count from track where id=?";     
    PreparedStatement checkStatement = con.prepareStatement(checkSql);
    String insertSql = "insert into track(id, artist, title, album, tuning, genre, url) values(?,?,?,?,?,?,?)";
    PreparedStatement insertStatement = con.prepareStatement(insertSql);
    String updateSql = "update track set artist=?, title=?, album=?, tuning=?, genre=?, url=? where id=?";
    PreparedStatement updateStatement = con.prepareStatement(updateSql);


    for(Track track: tracks){
        int id = track.getId();
        String artist = track.getArtist();
        String title = track.getTitle();
        String album = track.getAlbum();
        String tuning = track.getTuning();
        String genre = track.getGenre();
        String url = track.getFileUrl();

        checkStatement.setInt(1, id);
        ResultSet checkResult = checkStatement.executeQuery();
        checkResult.next();
        int count = checkResult.getInt(1);

        if (count == 0){
            System.out.println("Inserting track with ID: " + id);
            int col = 1;
            insertStatement.setInt(col++, id);
            insertStatement.setString(col++, artist);
            insertStatement.setString(col++, title);
            insertStatement.setString(col++, album);
            insertStatement.setString(col++, tuning);
            insertStatement.setString(col++, genre);
            insertStatement.setString(col++, url);
            insertStatement.executeUpdate();
            System.out.println(insertStatement.toString());
        } else {
            System.out.println("Updating track with ID: " + id);
            int col = 1;
            updateStatement.setString(col++, artist);
            updateStatement.setString(col++, title);
            updateStatement.setString(col++, album);
            updateStatement.setString(col++, tuning);
            updateStatement.setString(col++, genre);
            updateStatement.setString(col++, url);
            updateStatement.setInt(col++, id);
            updateStatement.executeUpdate();
        }
    }
    updateStatement.close();
    insertStatement.close();
    checkStatement.close();
}

Finally a track can be deleted by id.

public void deleteTrack(int id) throws SQLException{
    String checkSql = "select count(*) as count from track where id=?";
    PreparedStatement checkStatement = con.prepareStatement(checkSql);
    checkStatement.setInt(1, id);
    ResultSet checkResult = checkStatement.executeQuery();
    checkResult.next();
    int count = checkResult.getInt(1);
    if(count!=0){
        for(Iterator<Track> it=tracks.iterator(); it.hasNext(); ) {
        if(it.next().getId()==id) { 
            System.out.println(it);
            it.remove();
            break;
            }
        }
        System.out.println("Deleting track with ID: " + id);
        String deleteSql = "delete from track where id=?"; 
        PreparedStatement deleteStatement = con.prepareStatement(deleteSql);
        deleteStatement.setInt(1, id);
        deleteStatement.executeUpdate();
        deleteStatement.close();
    }
    checkStatement.close();
}

Any advice (on either part or whole) is welcome.