using (DataContext dc = new DataContext())
        {
            var q = from t in dc.TableTests
                    group t by t.SerialNumber
                        into g
                        select new
                        {
                            SerialNumber = g.Key,
                            uid = (from t2 in g select t2.uid).Max()
                        };
        }

var q = from s in db.Serials
        group s by s.Serial_Number into g
        select new {Serial_Number = g.Key, MaxUid = g.Max(s => s.uid) }

在方法链形式中：

db.Serials.GroupBy(i => i.Serial_Number).Select(g => new
    {
        Serial_Number = g.Key,
        uid = g.Max(row => row.uid)
    });

我在LinqPad里查了DamienG的答案

g.Group.Max(s => s.uid)

应该是

g.Max(s => s.uid)

谢谢你，谢谢你

如果您只需要这两个字段，答案是可以的，但是对于更复杂的对象，这种方法可能会很有用：

from x in db.Serials 
group x by x.Serial_Number into g 
orderby g.Key 
select g.OrderByDescending(z => z.uid)
.FirstOrDefault()

...这将避免“选择新的”

这可以在LINQ lambda表达式中使用GroupBy和SelectMany来完成

var groupByMax = list.GroupBy(x=>x.item1).SelectMany(y=>y.Where(z=>z.item2 == y.Max(i=>i.item2)));

基于以上所述，我希望将每组中的最佳结果放入与原始列表类型相同的列表中：

var bests = from x in origRecords
            group x by x.EventDescriptionGenderView into g
            orderby g.Key
            select g.OrderByDescending(z => z.AgeGrade)
            .FirstOrDefault();

    List<MasterRecordResultClaim> records = new 
                  List<MasterRecordResultClaim>();
    foreach (var bestresult in bests)
    {
        records.Add(bestresult);
    }

EventDescriptionGenderView是将几个字段合并为一个字符串。它为每个事件挑选最佳AgeGrade。