基于联接表向LINQ查询添加计数列

Question

因此，我已经创建了一个SQL视图，该视图可以提供所需的信息。 从本质上讲，这是一个工作职位空缺系统，用于显示已批准或填补（或分配）了多少个职位。

SELECT Companies.Name AS Company, Grades.Name AS Grade, Series.Name
AS Series, Positions.Authorized, COUNT(People.PersonId) AS Assigned

FROM Companies INNER JOIN
     Positions ON Companies.Id = Positions.CompanyId INNER JOIN
     Series ON Positions.SeriesId = Series.Id INNER JOIN
     Grades ON Positions.GradeId = Grades.Id INNER JOIN
     People ON Positions.CompanyId = People.CompanyId AND
     Positions.SeriesId = People.SeriesId AND Positions.GradeId = People.GradeId

GROUP BY Companies.Name, Grades.Name, Series.Name, Positions.Authorized

现在，我想做的就是在LINQ查询中重新创建它。 我几乎在需要的地方得到它； 但是，我不知道如何在基于People表的末尾添加计数列。

这是我当前的LINQ查询：

var query = from a in db.Companies
            join b in db.Positions on a.Id equals b.CompanyId
            join c in db.Series on b.SeriesId equals c.Id
            join d in db.Grades on b.GradeId equals d.Id
            join e in db.People on new { b.CompanyId, b.SeriesId, b.GradeId } equals new { e.CompanyId, e.SeriesId, e.GradeId }
            group a by new { CompanyName = a.Name, GradeName = d.Name, SeriesName = c.Name, b.Authorized, e.PersonId } into f
            select new { Company = f.Key.CompanyName, Grade = f.Key.GradeName, Series = f.Key.SeriesName, f.Key.Authorized, Assigned = /* needs to be Count(People.PersonId) based on last join */ )};

预先感谢您提供的任何帮助！

Answer 1

弄清楚了。 之所以发布多行而不是对同一行进行正确计数，是因为在我的“ group by”中，我应该在应该简单删除的情况下在“ e.PersonId”中添加它。 我还必须添加一些内容以使其在前端剃刀视图上工作，因为它是匿名类型（这与原始问题无关，但以为我会给出更改的理由）。 所以删除答案的人，您在某种程度上是正确的，但之所以无效，是因为该组中的其他字段：

dynamic query = (from a in db.Companies
                    join b in db.Positions on a.Id equals b.CompanyId
                    join c in db.Series on b.SeriesId equals c.Id
                    join d in db.Grades on b.GradeId equals d.Id
                    join e in db.People on new { b.CompanyId, b.SeriesId, b.GradeId } equals new { e.CompanyId, e.SeriesId, e.GradeId }
                    group a by new { CompanyName = a.Name, GradeName = d.Name, SeriesName = c.Name, b.Authorized } into f
                    select new { Company = f.Key.CompanyName, Grade = f.Key.GradeName, Series = f.Key.SeriesName, Authorized = f.Key.Authorized, Assigned = f.Count()}).AsEnumerable().Select(r => r.ToExpando());

以及页面上的外观：