Linq distinct＆max

我要查询这个表：

symbol time ------ ---------- aaa 2013-04-18 09:10:28.000 bbb 2013-04-18 09:10:27.000 aaa 2013-04-18 09:10:27.000 bbb 2013-04-18 09:10:26.000 

对于具有最大时间值的所有不同符号，我需要一行 。 我怎么写我的linq查询？

提前致谢，

Answer 1

按行分组行，然后从具有最大时间的每个组项中选择（ 表是上下文中的数据库表名）：

 from r in Table group r by r.symbol into g select g.OrderByDescending(x => x.time).First() 

与方法语法相同：

 Table.GroupBy(r => r.symbol) .Select(g => g.OrderByDescending(x => x.time).First()); 

Answer 2

试试这个

 var q = MyTable.GroupBy(x => x.symbol ) .Select(g => g.OrderByDescending(i => i.time).First()); 

或者像这样使用max

  var data = from r in MyTable group r by r.symbol into g select new { name= g.Key, data= g.Max(a=>a.time) }; 

Answer 3

我实际上会用。

 void Main() { var set = new [] { new Foo{A = "aaa", B = 1}, new Foo{A = "bbb", B = 2}, new Foo{A = "aaa", B = 3}, new Foo{A = "bbb", B = 4}, }; var result = from x in set group xB by xA into g select new {id = g.Key, biggest = g.Max()}; Console.WriteLine(result); } 

Answer 4

你可以使用Linq的lambda表达式 –

 var result= (from li in List.Distinct().OrderByDescending(x => x.time) select li).FirstOrDefault();