private ResultSet executeQuery(String sql)
    {
        ResultSet retres;
        Statement st;
        try
        {
            Log.logi("Start execution.");
            st = connection.createStatement();
            retres = st.executeQuery(sql);
           // st.close();
            Log.logi("End execution.");
            return retres;
        } catch (SQLException ex)
        {
            Log.loge(ex.getMessage());
        }
        
        return null;
    }