运行 SQLQuery 按日期计算行数

Question

我不擅长 Entity Framework，但计划运行原始查询。现在我坚持这个。使用以下代码时，出现以下错误。

Error CS1061 'Respons' does not contain a definition for 'TotalCount' and no extension method 'Total' accepting a first argument of type 'Respons' could be found (are you missing a using directive or an assembly reference?)

当我运行在 SSMS 中进行相同的查询时，我得到了以下结果。

Respons.cs

namespace Survey.Models
{
    using System;
    using System.Collections.Generic;

    public partial class Respons
    {
        public int ResponseID { get; set; }
        public string Username { get; set; }
        public string Name { get; set; }
        public string EmailAddress { get; set; }
        public Nullable<System.DateTime> DateTime { get; set; }
    }
}

原始查询

DbSqlQuery<Respons> Responses = DbContext.Responses.SqlQuery("SELECT max(ResponseID) AS ResponseID, COUNT(CreatedDateTime) AS Total, MAX(FORMAT(CreatedDateTime, 'dd-MMM-yyyy', 'en-US' )) as Date FROM Responses GROUP BY CAST(CreatedDateTime AS DATE) ORDER BY Date DESC");
foreach ( var r in Responses ){
   Response.Write( r.TotalCount);
}

Answer 1

先做一个ViewModelclass如下：

public class TotalCountByDateViewModel
{
   public int TotalCount { get; set; }
   public string Date { get; set; }
}

现在按如下方式编写您的查询：

DbSqlQuery<TotalCountByDateViewModel> totalCountsByDate = DbContext.Responses
  .SqlQuery("SELECT max(ResponseID) AS ResponseID, COUNT(CreatedDateTime)
  AS Total, MAX(FORMAT(CreatedDateTime, 'dd-MMM-yyyy', 'en-US' ))
  as Date FROM Responses GROUP BY CAST(CreatedDateTime AS DATE) ORDER BY Date DESC");

Answer 2

嗯，从消息中可以很清楚地看出您的 class 丢失了 "Total count" 属性。

group by query的写法参考这个link:

LINQ GroupBy translation

运行 SQLQuery 按日期计算行数

Running SqlQuery to count rows by date

entity-framework-5