如何选择只与LINQ最高日纪录 [英] How to select only the records with the highest date in LINQ

问题描述

我有一个表，lasttraces，具有以下字段。

I have a table, 'lasttraces', with the following fields.

Id, AccountId, Version, DownloadNo, Date

中的数据是这样的：

The data looks like this:

28092|15240000|1.0.7.1782|2009040004731|2009-01-20 13:10:22.000
28094|61615000|1.0.7.1782|2009040007696|2009-01-20 13:11:38.000
28095|95317000|1.0.7.1782|2009040007695|2009-01-20 13:10:18.000
28101|15240000|1.0.7.1782|2009040004740|2009-01-20 14:10:22.000
28103|61615000|1.0.7.1782|2009040007690|2009-01-20 14:11:38.000
28104|95317000|1.0.7.1782|2009040007710|2009-01-20 14:10:18.000

我怎样才能在 LINQ＆NBSP;到＆NBSP; SQL ，只有让每一个的AccountId的最后lasttrace（中具有最高日）？

How can I, in LINQ to SQL, only get the last lasttrace of every AccountId (the one with the highest date)?

推荐答案

如果你只是想的最后日期为每个帐户，你会使用这样的：

If you just want the last date for each account, you'd use this:

var q = from n in table
        group n by n.AccountId into g
        select new {AccountId = g.Key, Date = g.Max(t=>t.Date)};

如果你想整个纪录：

var q = from n in table
        group n by n.AccountId into g
        select g.OrderByDescending(t=>t.Date).FirstOrDefault();

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