C# ling to sql group by分组查询

(from b in _db.order_info
                             where b.status != 3
                             group new {  b.batchnumber, b.create_time } by new { b.merchant_id, b.batchnumber } into g
                             select new UserModel
                             {
                                
                                 batchnumber = g.Key.batchnumber,
                                 batchTime = g.Max(u => u.create_time)

                             }).OrderBy(p => p.batchTime).Take(20).ToList();