<p:commandButton id='extractTimesheetButton'
            actionListener  ="#{dataProcessingManagedBean.extractTimesheetData}"
            binding ="#{dataProcessingManagedBean.extractTimesheetCommandButton}" immediate="true"
            update='myForm:tabview:detailDataTable myForm:tabview:summaryDataTable myForm:downloadExcelsButton'
            ajax="false" icon="ui-icon-calculator" onclick="PF('statusDialog1').show()"   >

public void extractTimesheetData() throws SQLException, ClassNotFoundException, IOException {
    String fromDate = dateFormat.format( ((Date)fromDateCalendar.getValue())  );
    String toDate   = dateFormat.format( ((Date)  toDateCalendar.getValue())  );

    String sqlFromDate = sqlDateFormat.format( ((Date)fromDateCalendar.getValue())  );
    String sqltoDate = sqlDateFormat.format( ((Date)toDateCalendar.getValue())  );

    detailDataCount = 0;
    summaryDataCount = 0;

    Class.forName(COM_MYSQL_JDBC_DRIVER);
    Connection connection = DriverManager.getConnection(CONNECTION_STRING, USERNAME, PASSWORD);
    Statement statement = connection.createStatement();

    long detailDataStartTime = System.currentTimeMillis();
    queryDetailData(sqlFromDate, sqltoDate, statement);
    System.out.println("Detail Time takes "+ ((System.currentTimeMillis() - detailDataStartTime) /1000) + " seconds");
    long summaryDataStartTime = System.currentTimeMillis();
    querySummaryData(fromDate, toDate, statement);
    System.out.println("Summary Time takes "+ ((System.currentTimeMillis() - summaryDataStartTime) /1000) + " seconds");

    downloadExcelsCommandButton.setDisabled(!( detailDatas != null && detailDatas.size() > 0 && summaryDatas != null && summaryDatas.size() > 0 ));
    downloadExcelsCommandButton.setValue("Download excel file of data between " + fileNameDateFormat.format( this.fromDate ) +" and " + fileNameDateFormat.format( this.toDate ) );

    connection.close();
}