Question

我有5张桌子：

NazelShifts

Nazel

罐

PersonnelNazelShifts

移

sql查询是：

SELECT     SUM(NazelShift.Eold) AS tEold, SUM(NazelShift.Er) AS tEr,     SUM(NazelShift.Ecf) AS tEcf, SUM(NazelShift.Esf) AS tEsf, SUM(NazelShift.ESale) AS tESale, Tank.FuelId, 
                      NazelShift.ShiftId, PersonnelNazelShift.PersonnelId
FROM        NazelShift INNER JOIN
                      Nazel ON NazelShift.NazelId = Nazel.NazelId AND NazelShift.NazelId = Nazel.NazelId INNER JOIN
                      Tank ON Nazel.TankId = Tank.TankId INNER JOIN
                      PersonnelNazelShift ON Nazel.NazelId = PersonnelNazelShift.NazelId INNER JOIN
                      Shift ON NazelShift.ShiftId = Shift.ShiftId AND PersonnelNazelShift.ShiftId = Shift.ShiftId
WHERE     (NazelShift.ShiftId = 1)
GROUP BY Tank.FuelId, NazelShift.ShiftId, PersonnelNazelShift.PersonnelId

NazelShift与Nazel和Shift有很多对话 PersonnelNazelShift也与Nazel和Shift有很多关系。

图表为http://jmp.sh/dlO3MTf

我需要运行此查询：

NazelShifts.Where(i => i.ShiftId == 1)
    .GroupBy(i => new 
    { 
        i.ShiftId,         
        i.Nazel.Tank.FuelId,
        i.Nazel.PersonnelNazelShifts.SingleOrDefault().PersonnelId 
    })
    .Select(i => new
    {
        i.Key.ShiftId,
        i.Key.PersonnelId,
        i.Key.FuelId,
        tEold = i.Sum(rr => rr.Eold),
        tEr = i.Sum(rr => rr.Er),
        tEcf = i.Sum(rr => rr.Ecf),
        tEsf = i.Sum(rr => rr.Esf),
        tESale = i.Sum(rr => rr.ESale)
    })

这在LinqPad4中运行良好，但在vs2012中引发异常：

＆＃34;方法＆＃39; Single＆＃39;和＆＃39; SingleOrDefault＆＃39;只能用作最终查询操作。考虑使用方法＆＃39; FirstOrDefault＆＃39;在相反，这个实例。＆＃34;

我该如何解决这个问题？

在EF中使用SingleOrDefault进行GroupBy

0 个答案: