public IActionResult DeleteDiscount(int discountId)
 {
     if (discountId <= 0 || _discountCouponService.Count(x => x.Id == discountId) == 0)
     {
         return(NotFound());
     }
     _discountCouponService.Delete(x => x.Id == discountId);
     return(R.Success.Result);
 }