如何基于C＃实体框架中的另一个字段获取记录数？

Question

我有一个表格，存储患者的预约时间和日期。可以在一天的同一时间为多于一名的患者进行预约。

我的桌子看起来像这样：

|    Date    |  Time |  PatientID |
+------------+-------+------------+
| 2020/06/08 | 12:00 |      12    |
| 2020/06/08 | 12:00 |      15    |
| 2020/06/08 | 12:00 |      17    | 
| 2020/06/08 | 13:00 |      20    | 
| 2020/06/08 | 13:00 |      14    | 

我需要在gridview中显示'Time'和每次的计数。我的意思是：

|  Time |  Count |
+-------+--------+
| 12:00 |   3    |
| 13:00 |   2    |

我该怎么做？

我尝试过的-第一次尝试：

public List<Tbl_FutureTurnLocalModel> getReservedTime(int BillDate)
{
    List<Tbl_FutureTurnLocalModel> _reservedTime = _ClinicEntities.Tbl_ImagingFutureTurnDetail
         .Where(w => w.TurnDate == BillDate)
         .OrderBy(o => o.TurnTime)
         .Select(s => new Tbl_FutureTurnLocalModel
         {
             ReservedBillTime = s.TurnTime,
             ReservedCount = s.TurnTime.Count()
         })
         .ToList();

     return _reservedTime;
}

[Tbl_FutureTurnLocalModel是：

public partial class Tbl_FutureTurnLocalModel
{
    public string ReservedBillTime { get; set; }
    public int ReservedCount { get; set; }
}

但是会引发错误：

dbdistinctexpression需要集合参数。参数名称参数

SO中对同一问题的回答说：

public List<Tbl_FutureTurnLocalModel> getReservedTime(int BillDate)
{
    List<Tbl_FutureTurnLocalModel> _reservedTime = _ClinicEntities.Tbl_ImagingFutureTurnDetail
         .Where(w => w.TurnDate == BillDate)
         .OrderBy(o => o.TurnTime)
         .Select(s => new Tbl_FutureTurnLocalModel
         {
             ReservedBillTime = s.TurnTime,
             ReservedCount = s.Count()
         })
         .ToList();

     return _reservedTime;
}

但是出现调试时间错误。

Answer 1

.OrderBy(x => x.Time).GroupBy(x => x.Time).Select(x => new {x.Time})