如何使用group by，aggregate和join将SQL查询转换为Entity Framework查询？

Question

所以，我一直在尝试将下面的SQL查询转换为实体框架查询。我一直在寻找使用group by的其他问题，但是当我遵循相同的语法时，我无法让我工作。这是SQL查询：

SELECT w.WorkstationID, WorkstationName, MinEmployeeCount, 
OptimalEmployeeCount, MAX(Quantity) AS NumOfEmployees
FROM Workstation AS w
JOIN WorkstationRecord AS r
ON w.WorkstationID = r.WorkstationID
GROUP BY w.WorkstationID, WorkstationName, MinEmployeeCount, 
OptimalEmployeeCount

目前，我尝试了几种不同的EF查询（在查询语法中）：

Workstations = (from sta in context.Workstations
                          join rec in context.WorkstationRecords on sta.WorkstationID equals rec.WorkstationID
                          group sta by sta.WorkstationID into sta
                          select new ClientWorkstation()
                          {
                              WorkstationID = sta.WorkstationID,
                              WorkstationName = sta.WorkstationName,
                              MinEmployeeCount = sta.MinEmployeeCount,
                              OptimalEmployeeCount = sta.OptimalEmployeeCount,
                              NumOfEmployees = rec.Quantity,
                          }).ToList();

感谢任何帮助。

Answer 1

改变这个：

group sta by sta.WorkstationID into sta

到

group sta by new { sta.WorkstationID, sta.WorkstationName, sta.MinEmployeeCount, 
sta.OptimalEmployeeCount } into grp
select new ClientWorkstation
{
    // Are you sure you want Max and not Count?
    NumOfEmployees = grp.Max(t => t.Quantity), 
    // other members...
}