public string Create(dmLoaiNghiNganHan model)
        {
            if (model.stt <= 0)
            {
                return("STT phải lớn hơn 0!");
            }
            if (ModelState.IsValid)
            {
                db.dmLoaiNghiNganHan.Add(model);
                db.SaveChanges();
                return("OK");
            }

            return("ModelState Invalid!");
        }
 public string Edit(dmLoaiNghiNganHan model)
 {
     if (model.stt <= 0)
     {
         return("STT phải lớn hơn 0!");
     }
     if (ModelState.IsValid)
     {
         var nghi = db.dmLoaiNghiNganHan.AsNoTracking().Single(dm => dm.id == model.id);
         if (nghi.stt != model.stt)
         {
             db.dmLoaiNghiNganHan.Where(dm => dm.stt >= model.stt).ToList().ForEach(
                 dm => { dm.stt++;
                         db.Entry(dm).State = EntityState.Modified; });
         }
         db.Entry(model).State = EntityState.Modified;
         db.SaveChanges();
         return("OK");
     }
     return("ModelState Invalid!");
 }