public bool UpdateClass(T_DERS t_DERS)
 {
     try
     {
         using (DBOBISEntities entities = new DBOBISEntities())
         {
             var updateClass = entities.T_DERS.Where(x => x.DERS_KODU == t_DERS.DERS_KODU).FirstOrDefault();
             if (updateClass == null)
             {
                 return(false);
             }
             else
             {
                 updateClass.DERS_AKADEMİSYENI = t_DERS.DERS_AKADEMİSYENI;
                 updateClass.DERS_BLOCK        = t_DERS.DERS_BLOCK;
                 updateClass.DERS_ISMI         = t_DERS.DERS_ISMI;
                 updateClass.DERS_KODU         = t_DERS.DERS_KODU;
                 updateClass.DERS_SINIF_KOD    = t_DERS.DERS_SINIF_KOD;
                 return(true);
             }
         }
     }
     catch (Exception ex)
     {
         throw ex;
     }
 }
 public bool AddnewClass(T_DERS t_DERS)
 {
     try
     {
         using (DBOBISEntities entities = new DBOBISEntities())
         {
             var check = entities.T_DERS.Where(x => x.DERS_KODU == t_DERS.DERS_KODU).FirstOrDefault();
             if (check != null)
             {
                 return(false);
             }
             else
             {
                 entities.T_DERS.Add(t_DERS);
                 entities.SaveChanges();
                 return(true);
             }
         }
     }
     catch (Exception ex)
     {
         throw ex;
     }
 }