public void DodajObrisiPristupe(JTable tabela, JComboBox<String> korisnickoime)
{
    DefaultTableModel model = (DefaultTableModel)tabela.getModel();

    for (int i = 0; i < model.getRowCount(); i++)
    {
        String serijskibroj = model.getValueAt(i, 2).toString();
        boolean pristup = (Boolean)model.getValueAt(i, 4);

        if(ProveriDaLiPostojiPristup(serijskibroj, korisnickoime.getSelectedItem().toString()) == true)
        {
            if(pristup == false)
                ObrisiPristup(serijskibroj, korisnickoime.getSelectedItem().toString());
        }

        else
        {
            if(pristup == true)
                DodajPristup(serijskibroj, korisnickoime.getSelectedItem().toString());
        }
    }
}

public boolean ProveriDaLiPostojiPristup(String serijskibroj, String korisnickoime)
{
    Connection c = null;
    Statement stmt = null;

    try {

        Class.forName("org.sqlite.JDBC");
        c = DriverManager.getConnection("jdbc:sqlite:" + naziv + ".db");

        stmt = c.createStatement();

        ResultSet rs = stmt.executeQuery("SELECT * FROM PRISTUPI;");

        while(rs.next())
        {
            if(Decrypt(rs.getString("korisnickoime")).equals(korisnickoime) && Decrypt(rs.getString("vage")).equals(serijskibroj))
                return true;
        }

        rs.close();
        stmt.close();
        c.close();
    }
    catch ( Exception e ) {

        System.err.println( e.getClass().getName() + ": " + e.getMessage() );
        System.exit(0);
    }

    return false;
}

public void DodajPristup(String serijskibroj, String korisnickoime)
{
    Connection c = null;
    Statement stmt = null;

    try {

        Class.forName("org.sqlite.JDBC");
        c = DriverManager.getConnection("jdbc:sqlite:" + naziv + ".db");

        stmt = c.createStatement();

        String sql = "INSERT INTO PRISTUPI (KORISNICKOIME,VAGE) " +
                  "VALUES ('" + Encrypt(korisnickoime) + "', '" + Encrypt(serijskibroj) + "');";
        stmt.executeUpdate(sql);

        stmt.close();
        c.close();
    }
    catch ( Exception e ) {

        System.err.println( e.getClass().getName() + ": " + e.getMessage() );
        System.exit(0);
    }
}

public void ObrisiPristup(String serijskibroj, String korisnickoime)
{
    Connection c = null;
    Statement stmt = null;

    try {

        Class.forName("org.sqlite.JDBC");
        c = DriverManager.getConnection("jdbc:sqlite:" + naziv + ".db");

        stmt = c.createStatement();

        String sql = "DELETE from PRISTUPI where KORISNICKOIME = '" + Encrypt(korisnickoime) + "' AND VAGE = '" + Encrypt(serijskibroj) + "';";
        stmt.executeUpdate(sql);

        stmt.close();
        c.close();
    }
    catch ( Exception e ) {

        System.err.println( e.getClass().getName() + ": " + e.getMessage() );
        System.exit(0);
    }
}