/// <summary>
/// Handles the SelectedIndexChanged event of the ddlPeriodTrack control.
/// </summary>
/// <param name="sender">The source of the event.</param>
/// <param name="e">The <see cref="EventArgs"/> instance containing the event data.</param>
protected void ddlPeriod_SelectedIndexChanged(object sender, EventArgs e)
{
int periodId = ddlPeriod.SelectedValueAsInt() ?? 0;
var trackQry = new ResidencyService <Track>().Queryable().Where(a => a.PeriodId.Equals(periodId));
ddlTrack.DataSource = trackQry.OrderBy(a => a.DisplayOrder).ThenBy(a => a.Name).ToList();
ddlTrack.DataBind();
ddlTrack_SelectedIndexChanged(null, null);
}