public int Login([System.Web.Http.FromBody] NhanVien nv)
        {
            int ret             = 0;
            DBCNLTTH_BanSach db = new DBCNLTTH_BanSach();
            var data            = db.NhanViens.Where(x => x.TenTaiKhoan == nv.TenTaiKhoan.Trim() && x.MatKhau == nv.MatKhau).FirstOrDefault();

            if (data == null)
            {
                ret = 0;
            }
            else
            {
                ret = 1;
            }
            return(ret);
        }