void ICedts_UserRepository.ChangeUser(CEDTS_User user)
        {
            var id      = user.UserID;
            var olduser = db.CEDTS_User.Where(p => p.UserID == id).FirstOrDefault();

            db.ApplyCurrentValues(olduser.EntityKey.EntitySetName, user);
            db.SaveChanges();
        }
        void ICedts_UserRepository.Create(CEDTS_User user)
        {
            user.Role         = "普通用户";
            user.RegisterTime = DateTime.Now;
            if (user.ClassID == Guid.Empty)
            {
                user.ClassID   = null;
                user.GradeID   = null;
                user.MajorID   = null;
                user.PartnerID = null;
            }

            db.AddToCEDTS_User(user);
            db.SaveChanges();
        }