protected void districtSendMedicineDropDownList_SelectedIndexChanged(object sender, EventArgs e)
{
int id = int.Parse(districtSendMedicineDropDownList.SelectedValue);
thanaSendMedicineDropDownList.DataSource = centerManager.GetAllThana(id);
thanaSendMedicineDropDownList.DataTextField = "ThanaName";
thanaSendMedicineDropDownList.DataValueField = "Id";
thanaSendMedicineDropDownList.DataBind();
}