private void txtDate2_DateTimeChanged(object sender, EventArgs e)
{
var dc = new ClassSRMDataContext(Config.connection);
if (chkFilter.Checked)
{
int count = (cmbClass.Properties.DataSource as IList).Count;
if (count > 0)
{
int id = (int)cmbStudent.EditValue;
checkVBindingSource.DataSource = dc.Select2Dates(id, txtDate1.Text, txtDate2.Text);
}
}
}