public bool AddExportBill_Detail(export_bill_detail eb)
 {
     try
     {
         using (QLBH_PHONE_ENTITY data = new QLBH_PHONE_ENTITY())
         {
             data.export_bill_detail.Add(eb);
             data.SaveChanges();
             return(true);
         }
     }
     catch (Exception e)
     {
         Debug.WriteLine(e);
         return(false);
     }
 }
 public bool UpdateExportBill_Detail(export_bill_detail eb)
 {
     try
     {
         using (QLBH_PHONE_ENTITY data = new QLBH_PHONE_ENTITY())
         {
             data.Entry(eb).State = EntityState.Modified;
             data.SaveChanges();
             return(true);
         }
     }
     catch (Exception e)
     {
         Debug.WriteLine(e);
         return(false);
     }
 }