如何使用linq按多列分组

Question

我有一个数据集表,其中包含多行数据,如下所示

ItemId               Code                             StatusId
-------------------- ---------------------------------------------
62224                NC0860000                             8
62225                NC0860000                             8
62226                NC0860000                             8
62227                NC0860200                             5
62228                NC0860000                             5
62229                NC0860000                             5
62230                NC0860000                             5

我想要完成的是输出结果

NC0860000  8  3  (code, status, count)
NC0860000  5  3

我不完全理解分组在EF中是如何工作的.我可以使用查询获取密钥和单个组的计数:

var results = (from ssi in ctx.StageSubmitItems
                           join s in ctx.StageSubmissions on ssi.SubmissionId equals s.SubmissionId
                           where s.ContributorCode == contributorId
                           group ssi.SubmitItemId by ssi.AgencyCode into g
                           select new {AgencyCode = g.Key, Count = g.Count() }).ToList();

但我无法弄清楚如何按代码分组,然后按StatusId分组,然后按状态生成总行数.

我很感激有关如何在查询中查看如何完成此操作或我正在做什么的任何建议.

Answer 1

您可以按新的匿名类进行分组,如下所示:

// I created a Foo class to show this working
var fooList = new List<Foo> {
    new Foo { ItemId = 62224, Code = "NC0860000", StatusId = 8 },
    new Foo { ItemId = 62225, Code = "NC0860000", StatusId = 8 },
    new Foo { ItemId = 62226, Code = "NC0860000", StatusId = 8 },
    new Foo { ItemId = 62227, Code = "NC0860200", StatusId = 5 },
    new Foo { ItemId = 62228, Code = "NC0860000", StatusId = 5 },
    new Foo { ItemId = 62229, Code = "NC0860000", StatusId = 5 },
    new Foo { ItemId = 62230, Code = "NC0860000", StatusId = 5 },
};

var results = (from ssi in fooList
    // here I choose each field I want to group by
    group ssi by new { ssi.Code, ssi.StatusId } into g
    select new { AgencyCode = g.Key.Code, Status = g.Key.StatusId, Count = g.Count() }
).ToList();

// LINQPad output command
results.Dump();

提供数据,这是输出:

AgencyCode Status Count
NC0860000  8      3 
NC0860200  5      1 
NC0860000  5      3 

我猜"NC0860200"是一个错误,但它在你的样本数据中,所以我把它包括在内.