Linq C#，与多个查找相比，连接的性能更低

我有一个旧版本的代码，正在执行多重查找。我需要一些额外的字段，所以我重写了它来进行几个连接，并立即返回我需要的所有内容。我原以为这会有更好的性能，但当用秒表测试时，情况并非如此，而且速度相当慢。我是否无意中对我的查询做了一些错误

旧代码 新代码

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记录在两个查询之间生成的SQL。查看针对数据库生成的结果集。另外，是否尝试多次运行查询？EntityFramework在第一次查询时尤其慢，在同一查询的后续运行时则更快。返回了多少项？返回了41项。我确实试过并运行了几次，注意到了波动，它们现在更接近了，相距只有50毫秒左右，但通常旧代码似乎赢得了大多数尝试。我想检查它生成的SQL只是不确定如何生成。第一个查询似乎检索不到相同的数据，特别是

游戏

相关信息。另外，您最好使用导航属性，因为连接的基数不太清楚，因此GROUPBY操作符可能是多余的。

// ===============================old
            var watchOld = System.Diagnostics.Stopwatch.StartNew();
            var def = context.FDataMLBPlayers.Where(d => d.Status.Trim().ToLower().Equals("active") && d.Position.Trim().ToLower().Equals(position.ToLower())).OrderBy(d => d.Team);
            foreach (var dd in def)
            {
                bool addPlayer = false;
                foreach (var tm in teams)
                {
                    if (tm.Trim().Equals(dd.Team.Trim()))
                    {
                        addPlayer = true;
                        break;
                    }
                }
                if (!addPlayer) continue;
                Player player = new Player();
                player.Name = dd.FirstName.Trim() + " " + dd.LastName.Trim();
                player.LastName = dd.LastName.Trim();
                player.Number = dd.Jersey.HasValue ? dd.Jersey.Value : 0;
                player.PlayerID = dd.PlayerID;
                player.Points = 0;
                player.Position = (dd.Position == null) ? "" : dd.Position.Trim();
                player.Score = 0;
                player.Status = "Active";//DOROC dd.CurrentStatus;
                player.Team = dd.Team.Trim();
                htop ht = GetOpposingTeam(dd.Team.Trim()); //another lookup
                player.OpposingTeam = ht.OpposingTeam;
                player.PhotoUrl = dd.PhotoUrl.Trim();
                player.IsHomeTeam = ht.IsHomeTeam;
                if (dd.Position != null)
                {
                    list.Add(player);
                }
            }
            watchOld.Stop();
            var oldTime = watchOld.ElapsedMilliseconds; // 227 ms

// ========================================== new
            var watchNew = System.Diagnostics.Stopwatch.StartNew();
            var def2 = (from p in context.FDataMLBPlayers
                       join g in context.FDataMLBPlayerGames on p.PlayerID equals g.PlayerID
                       join t in context.FDataMLBTeams on g.OpponentID equals t.TeamID
                       where p.Status.Trim().ToLower().Equals("active")
                       && p.Position.Trim().ToLower().Equals(position.ToLower()) 
                       && teams.Contains(p.Team)
                       group new { p, g, t }
                       by new { p.PlayerID } into pgt
                       let fod = pgt.FirstOrDefault()
                       select new Player
                       {
                           DateTime = fod.g.DateTime.Value,
                           IsHomeTeam = fod.g.HomeOrAway.ToLower().Equals("home") ? true : false,
                           LastName = fod.p.LastName,
                           Name = fod.p.FirstName.Trim() + " " + fod.p.LastName.Trim(),
                           Number = fod.p.Jersey.HasValue ? fod.p.Jersey.Value : 0,
                           OpposingTeam = fod.t.Name,
                           PhotoUrl = fod.p.PhotoUrl,
                           PlayerID = fod.p.PlayerID,
                           Points = 0,
                           Position = fod.p.Position,
                           Score = 0,                              
                           Started = fod.g.Started.Value.Equals(1) ? true : false, 
                           Status = fod.p.Status, 
                           Team = fod.p.Team,       
                        }
                ).ToList();       
            list = def2;
            watchNew.Stop();
            var newTime = watchNew.ElapsedMilliseconds; // 399 ms