public IHttpActionResult PutDanDangKy(int id, DanDangKy danDangKy)
        {
            if (!ModelState.IsValid)
            {
                return(BadRequest(ModelState));
            }

            if (id != danDangKy.ma_dang_ky)
            {
                return(BadRequest());
            }

            db.Entry(danDangKy).State = EntityState.Modified;

            try
            {
                db.SaveChanges();
            }
            catch (DbUpdateConcurrencyException)
            {
                if (!DanDangKyExists(id))
                {
                    return(NotFound());
                }
                else
                {
                    throw;
                }
            }

            return(StatusCode(HttpStatusCode.NoContent));
        }
        public IHttpActionResult GetDanDangKy(int id)
        {
            DanDangKy danDangKy = db.DanDangKies.Find(id);

            if (danDangKy == null)
            {
                return(NotFound());
            }

            return(Ok(danDangKy));
        }
        public IHttpActionResult PostDanDangKy(DanDangKy danDangKy)
        {
            if (!ModelState.IsValid)
            {
                return(BadRequest(ModelState));
            }

            db.DanDangKies.Add(danDangKy);
            db.SaveChanges();

            return(CreatedAtRoute("DefaultApi", new { id = danDangKy.ma_dang_ky }, danDangKy));
        }
        public IHttpActionResult DeleteDanDangKy(int id)
        {
            DanDangKy danDangKy = db.DanDangKies.Find(id);

            if (danDangKy == null)
            {
                return(NotFound());
            }

            db.DanDangKies.Remove(danDangKy);
            db.SaveChanges();

            return(Ok(danDangKy));
        }