protected void thanaDropDownList_SelectedIndexChanged(object sender, EventArgs e)
{
int id = Convert.ToInt32(thanaDropDownList.SelectedValue);
centerDropDownList.DataSource = dropDownManager.GetAllCenter(id);
centerDropDownList.DataTextField = "Name";
centerDropDownList.DataValueField = "Id";
centerDropDownList.DataBind();
ListItem liCenter = new ListItem("Select Center", "-1");
centerDropDownList.Items.Insert(0, liCenter);
}
