linq 实现group by 不使用group关键字 等同lambad表达式中的group join 查询一对多关系

     return from orderInfo in orderEntity.x_s_orderInfo

                      join oState in orderEntity.x_s_oStatuInfo
                                       on orderInfo.oId equals oState.oId into t

                      select new OrderInfoModel
                      {
                         orderInfo= orderInfo,
                         // UserIDs = string.Join(",", t.Select(x => x.UserID.ToString()).ToArray())
                      };

　　关键在于 into

查询一对多关系

/// <summary>
/// 订单状态信息
/// </summary>
public IEnumerable<x_s_oStatuInfo> orderState { get; set; }

这里将订单状态改为集合类型

  select new OrderInfoModel
                      {
                         orderInfo= orderInfo,
                    orderState=t.Select(u=>u)
                      };