Question

我有一个数据集表，其数据集包含多行数据，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

我不完全了解分组在EF中的工作原理。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错误操作的建议。

Answer 1

您可以按照以下方式按新的匿名类进行分组：

// 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();

根据提供的数据，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。

如何使用linq按多列分组

1 个答案: