在Linq's Group中按左连接的多列进行条件计数

Question

我知道有很多类似的问题，我已经解决了很多问题，但是仍然无法掌握如何在LINQ中解决问题。 我需要创建一个获取数据的查询，作为此纯SQL查询：

SELECT p.ProcessId, p.Description, p.StartedOn, p.StartedBy, uuus.Name + ' ' + uuus.Surname AS StartedByName, p.FinishedOn, p.FinishedBy, uuu.Name + ' ' + uuu.Surname as FinishedByName, p.PlannedFinish, p.PlannedStart, COUNT(CASE WHEN h.IsCompleted IS NULL AND h.HandlingId IS NOT NULL THEN 1 END)
FROM JDE_Processes p LEFT JOIN JDE_Users uuu ON p.FinishedBy = uuu.UserId LEFT JOIN JDE_Handlings h ON h.ProcessId=p.ProcessId LEFT JOIN JDE_Users uuus ON uuus.UserId=p.StartedBy
GROUP BY p.ProcessId, p.Description, p.StartedOn, p.StartedBy,uuus.Name + ' ' + uuus.Surname, p.FinishedOn, p.FinishedBy, uuu.Name + ' ' + uuu.Surname, p.PlannedFinish, p.PlannedStart, p.Createdon
ORDER BY p.CreatedOn DESC

这是我的linq版本，大多数情况下都可以使用，但是我无法弄清楚“如果h.IsCompleted = 0则计数”部分。

var items = (from p in db.JDE_Processes
    join uuu in db.JDE_Users on p.FinishedBy equals uuu.UserId into finished
    from fin in finished.DefaultIfEmpty()
    join h in db.JDE_Handlings on p.ProcessId equals h.ProcessId into hans
    from ha in hans.DefaultIfEmpty()
    group new { p, fin }
    by new {
        p.ProcessId,
        p.Description,
        p.StartedOn,
        p.StartedBy,
        p.FinishedOn,
        p.FinishedBy,
        p.PlannedFinish,
        p.PlannedStart,
        fin.Name,
        fin.Surname
    } into grp
    orderby grp.Key.ProcessId descending
    select new Process
    {
        ProcessId = grp.Key.ProcessId,
        Description = grp.Key.Description,
        StartedOn = grp.Key.StartedOn,
        StartedBy = grp.Key.StartedBy,
        FinishedOn = grp.Key.FinishedOn,
        FinishedBy = grp.Key.FinishedBy,
        FinishedByName = grp.Key.Name + " " + grp.Key.Surname,
        PlannedStart = grp.Key.PlannedStart,
        PlannedFinish = grp.Key.PlannedFinish,
        HandlingStatus = grp.Count().ToString()
    });

问题：

1）如何获得'计数如果h.IsCompleted = 0'工作？

2）我可以使用某种别名吗？ 我的意思是，在该查询的实际版本中join uuu in db.JDE_Users on p.StartedBy equals uuu.UserId into started from star in started.DefaultIfEmpty()还存在另一个左join uuu in db.JDE_Users on p.StartedBy equals uuu.UserId into started from star in started.DefaultIfEmpty()这导致我在grp中有2个Name和2个Surname列。 然后如何将适当的字段分配给适当的输出字段？ 我的意思是像下面这样：

select new Process
{
    ProcessId = grp.Key.ProcessId,
    Description = grp.Key.Description,
    StartedOn = grp.Key.StartedOn,
    StartedBy = grp.Key.StartedBy,
    StartedByName = grp.Key.Name + " " + grp.Key.Surname, // <-- how will it know which Name field to use? 
    FinishedOn = grp.Key.FinishedOn,
    FinishedBy = grp.Key.FinishedBy,
    FinishedByName = grp.Key.Name + " " + grp.Key.Surname,
    PlannedStart = grp.Key.PlannedStart,
    PlannedFinish = grp.Key.PlannedFinish,
    HandlingStatus = grp.Count().ToString()
}

Answer 1

我不确定这将有多大帮助，因为它是您的SQL的翻译，而您的LINQ似乎与您的SQL没有关系，但是我有：

var ans = from p in db.JDE_Processes
          join uuu in db.JDE_Users on p.FinishedBy equals uuu.UserId into uuuj
          from uuu in uuuj.DefaultIfEmpty()
          join h in db.JDE_Handlings on p.ProcessId equals h.ProcessId into hj
          from h in hj
          group new { p, h } by new { p.ProcessId, p.Description, p.StartedOn, p.StartedBy, p.FinishedOn, p.FinishedBy, p.PlannedFinish, p.PlannedStart } into phg
          select new {
              phg.Key.ProcessId,
              phg.Key.Description,
              phg.Key.StartedOn,
              phg.Key.StartedBy,
              phg.Key.FinishedOn,
              phg.Key.FinishedBy,
              phg.Key.PlannedFinish,
              phg.Key.PlannedStart,
              HandlingStatus = phg.Where(ph => ph.h.IsCompleted == null).Count()
          };

Answer 2

很抱歉回答我自己的问题，但我已经找到2的答案。 当我有两个同名属性（例如“ Surname”）时，我只是不知道如何为该属性创建别名。 请在下面找到包含别名以及NetMage解决的条件计数器部分的代码：

var items = (from p in db.JDE_Processes
                             join uuu in db.JDE_Users on p.FinishedBy equals uuu.UserId into finished
                             from fin in finished.DefaultIfEmpty()
                             join uu in db.JDE_Users on p.StartedBy equals uu.UserId into started
                             from star in started.DefaultIfEmpty()
                             join h in db.JDE_Handlings on p.ProcessId equals h.ProcessId into hans
                             from ha in hans.DefaultIfEmpty()
                             where p.TenantId == tenants.FirstOrDefault().TenantId && p.CreatedOn >= dFrom && p.CreatedOn <= dTo
                             group new { p, fin, star, ha }
                             by new {
                                 p.ProcessId,
                                 p.Description,
                                 p.StartedOn,
                                 p.StartedBy,
                                 p.FinishedOn,
                                 p.FinishedBy,
                                 p.PlannedFinish,
                                 p.PlannedStart,
                                 fin.Name,
                                 fin.Surname,
                                 StarterName = star.Name, // <-- Creating alias
                                 StarterSurname = star.Surname // <-- Creating alias
                             } into grp
                             orderby grp.Key.ProcessId descending
                             select new Process
                             {
                                 ProcessId = grp.Key.ProcessId,
                                 Description = grp.Key.Description,
                                 StartedOn = grp.Key.StartedOn,
                                 StartedBy = grp.Key.StartedBy,
                                 StartedByName = grp.Key.StarterName + " " + grp.Key.StarterSurname,
                                 FinishedOn = grp.Key.FinishedOn,
                                 FinishedBy = grp.Key.FinishedBy,
                                 FinishedByName = grp.Key.Name + " " + grp.Key.Surname,
                                 PlannedStart = grp.Key.PlannedStart,
                                 PlannedFinish = grp.Key.PlannedFinish,
                                 HandlingStatus = grp.Where(ph=>ph.ha.IsCompleted == null && ph.ha.HandlingId >0).Count().ToString()
                             });