我们如何使用Linq C＃左连接，计数，总和在其中执行选择到另一个选择

Question

如何将我的sql代码转换为Linq格式：

我们如何使用Linq c＃将一个选择转换为另一个选择：

我的SQL代码：

SELECT DepartementProjects.Label, a.Number FROM
(SELECT DepartementProjects.Label ,count(1) as Number FROM DepartementProjects
inner join Absences on DepartementProjects.Id = Absences.DepartementProjectID
where Absences.Profil='SHT'
group by DepartementProjects.Label ) a right join DepartementProjects on DepartementProjects.Label = a.Label;

我的尝试：

            var AbsByDepartmentADM = from department in _dbContext.DepartementProjects
                                 join abs in _dbContext.Absences on department.Id equals abs.DepartementProjectID
                                 into groupedResult 
                                 from groupedResultRight in groupedResult.DefaultIfEmpty()
                                 group groupedResultRight by department.Label into grouped
                                 let NumberOfAbsence = grouped.Count(t => t.DepartementProjectID != null)
                                 let WorkedHours = grouped.Sum(a => a.WorkedHours != null ? a.WorkedHours : 0)

                                  select new
                                  {
                                      DepartmentId = grouped.Key,
                                      NumberOfAbsence,
                                      WorkedHours,
                                      AbsencesHours = (8 * NumberOfAbsence - WorkedHours),

                                  };

Answer 1

如果要翻译SQL，请先翻译所有子选择，然后再翻译主选择，然后按LINQ短语顺序翻译。 另外，您的LINQ会在SQL中添加一些值，因此我没有尝试更改SQL以使其匹配：

var sub = from dept in _dbContext.DepartementProjects
      join abs in _dbContext.Absences on dept.Id equals abs.DepartementProjectID into absj
      from abs in absj
      where abs.Profil == "SHT"
      group abs by dept.Label into absg
      select new { Label = absg.Key, Number = absg.Count() };

var ans = from dept in _dbContext.DepartementProjects
      join a in sub on dept.Label equals a.Label into lnj
      from ln in lnj.DefaultIfEmpty()
      select new { dept.Label, ln.Number };