Linq中怎么取出每个用户的符合条件的第一条记录

Linq中如何取出每个用户的符合条件的第一条记录？
Linq中如何取出每个用户的符合条件的第一条记录？

数据库有以下几个字段：
主键用户id 名次时间是否正常
1 100 10 20101012 1
2 100 20 20101009 1
3 200 11 20101011 1
4 100 18 20101008 1
5 300 2 20101010 1
6 300 15 20101013 1
7 300 16 20101002 0
我要得到这样的结果：
100 18 20101008
200 11 20101011
300 2 20101010
请问这个用Linq怎么实现？？

------解决方案--------------------
根据时间排序
db.Tb
.OrderByDescending(x=> x.时间)
.group ...
.FirstOrDefault();
------解决方案--------------------
什么条件啊？？
------解决方案--------------------

C# code


  static void Main(string[] args)
        {
            var list = GetData();

            var query =
                    from u in list
                    where u.IsNormal == "1"
                    group u by u.UserId into g
                    orderby g.Key
                    from u2 in g
                    where u2.Date == g.Min(u3 => u3.Date)
                    select u2;

            foreach (var u in query)
                Console.WriteLine("{0}, {1}, {2}", u.UserId, u.Date, u.Rank);
            

            Console.Read();
        }

        static IEnumerable<User> GetData()
        {
            yield return new User { UserId = "100", Rank = "10", Date = "20101012", IsNormal = "1" };
            yield return new User { UserId = "100", Rank = "20", Date = "20101009", IsNormal = "1" };
            yield return new User { UserId = "200", Rank = "11", Date = "20101011", IsNormal = "1" };
            yield return new User { UserId = "100", Rank = "18", Date = "20101008", IsNormal = "1" };
            yield return new User { UserId = "300", Rank = "2", Date = "20101010", IsNormal = "1" };
            yield return new User { UserId = "300", Rank = "15", Date = "20101013", IsNormal = "1" };
            yield return new User { UserId = "300", Rank = "16", Date = "20101002", IsNormal = "0" };
        }

Linq中怎么取出每个用户的符合条件的第一条记录

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