LINQ to SQL的：数据来自两个不相关的表，对日期进行排序 [英] LINQ to SQL: Data from two unrelated tables, sorting on date

问题描述

我有两个表 tblActionLog 和 tblLoginLog 。

这是 tblActionLog ：

tblActionLog
------------
ID (int)
Happened (DateTime)
...etc.

这是 tblLoginLog ：

tblLoginLog
-----------
ID (int)
LoginDate (DateTime)
...etc.

现在我想有一个 GridView控件与这两个表中海誓山盟交错，使他们独立的日期信息进行排序的信息，例如：

Now I want to have a GridView with information from both of these tables interleaved in eachother so that their separate date informations are sorted, e.g.:

LOG OF STUFF
-------------------------------
DATE        |  WHAT     
2009-09-09  | Anderson logged in.
2009-09-08  | Smith made an action.
2009-09-08  | Smith logged in.
2009-09-06  | Anna made an action.
2009-09-04  | Smith made an action.

我希望这使得它很清楚。我想所有这些信息在一个单一的LINQ查询（不一定是一条SQL查询）。任何帮助AP preciated。

I hope this makes it clear enough. I want to get all of this information in a single LINQ query (not necessarily one SQL query). Any help appreciated.

推荐答案

您可能需要使用选择（）和联盟（）整理的结果。

You probably want to use Select() and Union() to collate the results.

var query = context.Logins.Where( l => l.UserID == userID )
                          .Select( l => new { Date = l.Date, What = "logged in" } )
                  .Union( context.Actions.Where( a => a.UserID == userID )
                                          .Select( a => new { Date = a.Date, What = a.Action  } ))
                  .OrderBy( r => r.Date );

注意：您可能需要兑现每个子查询（用了ToList（）或AsEnumerable（）），但我认为应该LINQ2SQL能够直接构建UNION。此外，这是完全未经测试 - 直接输入到答案编辑器，我没有检查工会法的签名，所以你可能需要调整

Note: you may need to materialize each subquery (use ToList() or AsEnumerable()), but I think LINQ2SQL should be able to construct the UNION directly. Also, this is completely untested - typed straight into the answer editor and I didn't check the signature of the Union method so you may need to adjust.

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