实体LINQ查询变慢

你的问题是 AsEnumerable . 当执行查询时(在您的情况下 results.ToList() ),之后显示的所有内容都将使用linq to objects进行计算。这意味着DB不会处理您的连接。您将从表中获取所有记录。

但是,您的功能 WashTypeShowEnum.WashTypeShowEnumToString 实体框架不会识别。

您可能需要移动 A可计算 直到最后,然后 select 结果。

var results = (from w in db.Washes
              join t in db.Wash_Types on w.WashTypeId equals t.Id
              join a in db.Accounts on w.AccountId equals a.Id
              orderby w.Id descending
              select new {w, a, t}).AsEnumerable().Select(arg=> new AllWashesTable
                    {
                        Id = arg.w.Id,
                        WashTime = arg.w.WashTime,
                        WashTimeEnd = arg.w.WashTimeEnd,
                        Name = arg.a.Name,
                        Client = (arg.w.Client != null ? arg.w.Client.Naziv : ""),
                        MobileNumber = arg.a.MobileNumber,
                        Identification = arg.w.Identification,
                        WashType = WashTypeShowEnum.WashTypeShowEnumToString((WashTypeShowEnum.WashType) arg.w.WashTypeId),
                        Price = int.Parse(arg.t.WashPrice) * (1 - arg.w.Discount) + "",
                        Discount = arg.w.Discount
                    };
return results.ToList();