public bool Insert_Bill(Bill b)
 {
     if ( b==null|| b.User_Id1 != Employee.Id || b.User_Id1==0  ||b.Date1.DayOfYear==1 )
     {
         return false;
     }
     else
     {
         return bill.Insert_Bill(b);
     }
 }
 public bool return_Bill_Id(Bill bill1)
 {
     if (bill1==null  || bill1.User_Id1<=0)
     {
         return false;
     }
     else
     {
         return bill.return_Bill_Id(bill1);
     }
 }
 public Order(List<BL.Product> product,List<int> quan,Bill bill)
 {
     this.B = bill;
     this.Product = product;
     this.Quantity = quan;
 }