LINQ groupby statement with key

Question

我的查詢語法很好，但不是輸出，它真的很奇怪。

我有以下表：

| AppointID | UserID | AppointSet | AppointResolved | AppointStatus | AppointmentDatetime 
|  1  | 1 | 3/1/2011 | 3/1/2011  |  1   |  3/15/2011 
|  2  | 1 | 3/2/2011 | 3/5/2011  |  4   |  3/16/2011 
|  3  | 1 | 3/2/2011 | 3/11/2011  |  2   |  3/11/2011 
|  4  | 1 | 3/3/2011 | 3/7/2011  |  3   |  3/25/2011 

ApponintStatus是一個字節，其中1是用於組，圖2是用於參加，圖3是用於經重組和圖4是用於取消。 AppointDatetime是約會設置的日期。

我想要做的就是創建下面的輸出，通過計算一天的活動。

| Date  | Set | Attended | Rescheduled | Cancelled | 
| 3/1/2011 | 1 |    |     |    | 
| 3/2/2011 | 2 |    |     |    | 
| 3/3/2011 | 1 |    |     |    | 
| 3/5/2011 |   |    |     |  1  | 
| 3/7/2011 |   |  1  |     |    | 
| 3/11/2011 |   |    |  1  |    | 

這是我到目前爲止。 TheDate是我查詢一個月內的日期（即，通過3月4日，應退還三月表）

var r = from appnt in MyDC.LeadsAppointments 
     where appnt.UserID == TheUserID 
     where (appnt.AppointResolved.Year == TheDate.Year && appnt.AppointResolved.Month == TheDate.Month) || 
     (appnt.AppointSet.Year == TheDate.Year && appnt.AppointSet.Month == TheDate.Month) 
     group appnt by appnt.AppointResolved.Date into daygroups 
     select new ViewMonthlyActivityModel() 
     { 
      ViewDate = (from d in daygroups 
         select daygroups.Key.Date).First(), // Problem here: need to get dates for instances where an appointment is set but none are resolved 

      CountTotalSetOnDay = (from c in daygroups 
            where c.AppointSet.Date == daygroups.Key // Problem here 
            select c.AppointID).Count(), 

      CountAttendedOnDay = (from c in daygroups 
            where c.AppointResolved.Date == daygroups.Key.Date 
            where c.AppointStatus == 2 
            select c.AppointID).Count(), 

一個問題是，CountTotalSetOnDay將返回只有那些設置和計數同一天解決;另一個問題是ViewDate需要返回所有的日期：有沒有設置約會但約會出席，重新安排或取消的日期，反之亦然，有約會設置但沒有解決的日期。

現在我有2個查詢運行此，我加入了結果：一個查詢返回設置的約會和其他收益的任命得到解決。然而，我仍然堅持在一次閱讀中一個查詢的解決方案。

有什麼建議嗎？

謝謝。

Answer 1

我猜這個解決方案有兩個讀取查詢的工作很好，現在就代表着。

Answer 2

你被AppointResolved.Date分組。

因此，對於daygroups中的每個條目，daygroups.Key == AppointResolved.Date和c.AppointSet.Date == daygroups.Key where子句將只給你約會設置在同一天的所有條目因爲它已經解決了。

在我看來，如果你想實現自己的既定目標，你必須列出你的任何表的字段中提到的所有日期和計數。

例如，請考慮：

var appointmentsTaken = (from appnt in GoyaDC.LeadsAppointments 
         where ... // your filters 
         group appnt by appnt.AppointSet.Date into daysset 
         select { Date = daysset.Key Count = daysset.Count() } 

這應該給你的日期列表，其中任命其中一組，併爲每個，其中有多少人。

Answer 3

您需要使用組同時設置日期和解決日期。這很容易通過添加另一個from子句與日期集合進行交叉連接並按這些日期分組來實現。

下面的查詢是基於LINQ到對象的查詢。 LINQ to SQL不支持這種查詢，因此您必須決定是否要使用在客戶機或服務器上運行的查詢。

const byte statusAttended = 2; 
const byte statusRescheduled = 3; 
const byte statusCancelled = 4; 
var query = from a in MyDC.LeadsAppointments.AsEnumerable() 
      from date in new[] { a.AppointSet.Date, a.AppointResolved.Date } 
      where a.UserID == TheUserID 
       && date.Year == TheDate.Year 
       && date.Month == TheDate.Month 
      group a by date into g 
      orderby g.Key 
      let set = g.Distinct().ToList() 
      select new ViewMonthlyActivityModel 
      { 
       ViewDate = g.Key, 
       CountTotalSetOnDay = 
        set.Count(a => a.AppointSet.Date == g.Key), 
       CountTotalAttendedOnDay = 
        set.Count(a => a.AppointResolved.Date == g.Key 
           && a.AppointStatus == statusAttended), 
       CountTotalRescheduledOnDay = 
        set.Count(a => a.AppointResolved.Date == g.Key 
           && a.AppointStatus == statusRescheduled), 
       CountTotalCancelledOnDay = 
        set.Count(a => a.AppointResolved.Date == g.Key 
           && a.AppointStatus == statusCancelled), 
      }; 

---

否則，對於一個完全的LINQ to SQL解決方案（不乾淨的）應該工作，你可以試試這個。可能有更好的方法來做到這一點，但我不知道。

const byte statusAttended = 2; 
const byte statusRescheduled = 3; 
const byte statusCancelled = 4; 
var query = from a in MyDC.LeadsAppointments 
      let setDate = from aa in MyDC.LeadsAppointments 
          where aa.AppointID == a.AppointID 
          select aa.AppointSet.Date 
      let resolvedDate = from aa in MyDC.LeadsAppointments 
           where aa.AppointID == a.AppointID 
           select aa.AppointResolved.Date 
      from date in setDate.Concat(resolvedDate) 
      where a.UserID == TheUserID 
       && date.Year == TheDate.Year 
       && date.Month == TheDate.Month 
      group a by date into g 
      orderby g.Key 
      let set = g.Distinct() 
      select new ViewMonthlyActivityModel 
      { 
       ViewDate = g.Key, 
       CountTotalSetOnDay = 
        set.Count(a => a.AppointSet.Date == g.Key), 
       CountTotalAttendedOnDay = 
        set.Count(a => a.AppointResolved.Date == g.Key 
           && a.AppointStatus == statusAttended), 
       CountTotalRescheduledOnDay = 
        set.Count(a => a.AppointResolved.Date == g.Key 
           && a.AppointStatus == statusRescheduled), 
       CountTotalCancelledOnDay = 
        set.Count(a => a.AppointResolved.Date == g.Key 
           && a.AppointStatus == statusCancelled), 
      };