private void buttonQuery_Click(object sender, EventArgs e)
{
string oper = "";
if (null != comboBoxOperator.SelectedItem)
{
oper = comboBoxOperator.SelectedItem.ToString();
}
dataGridViewLog.DataSource = logDao.getLog(textBoxModule.Text, oper,
dateTimePickerBegin.Value.Date, dateTimePickerEnd.Value.Date).Tables[0].DefaultView;
}