Question

我的查询的语法很好但不是输出，这真的很奇怪。

我有下表：

| 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是一个字节，其中1代表set，2代表有人参与，3代表重新安排，4代表取消。 AppointDatetime是约会的日期。

我要做的是创建以下输出，按日计算活动。

|    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        |               |

这是我到目前为止所拥有的。 TheDate是我要查询的月份内的日期（即3月4日通过，应该返回March表格）

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(),

其中一个问题是CountTotalSetOnDay仅返回当天设置和解析的计数;另一个问题是ViewDate需要返回所有日期：有没有设置约会但是约会参加，重新安排或取消的日期，反之亦然，有约会设置但没有解决的日期。

现在，我正在使用2个查询来运行此操作并加入结果：一个查询返回约会集，另一个返回已解决的约会。但是，我仍然坚持使用一次查询中的一个查询解决方案。

有什么建议吗？

感谢。

Answer 1

您需要使用设置日期和已解决的日期进行分组。这可以通过添加另一个from子句来实现，该子句使用日期集进行交叉连接并按这些日期进行分组。

以下查询基于LINQ to Objects查询。 LINQ to SQL不支持这种查询，因此您必须决定是否要使用在客户端计算机或服务器上运行的查询。

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),
            };

否则对于应该工作的完全LINQ to SQL解决方案（不是最干净的），你可以试试这个。可能有更好的方法可以做到这一点，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),
            };

Answer 2

您正在按照AppointResolved.Date进行分组。

因此，对于daygroups中的每个条目，daygroups.Key == AppointResolved.Date，以及c.AppointSet.Date == daygroups.Key where子句将仅为您提供在同一天设置约会的所有条目它得到了解决。

在我看来，如果你想达到既定目标，你必须列出你桌子上任何一个字段中提到的所有日期并计算它们。

例如，考虑：

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() }

这应该会为您提供一个列表，其中列出了约会的设定日期，以及每个约会的约会数量。

Answer 3

我猜有2个读取查询的解决方案工作得很好，现在就可以了。

LINQ groupby语句带键

3 个答案: