在EF4中将Sql Pivot表查询转换为linq

Question

过去三天我一直在做一项任务。我尝试将一个SQL查询转换为linq，它基于“将列转换为行”，称为数据透视表。

我的SQL查询如下。

SELECT project_name
,SUNDAY
,MONDAY
,TUESDAY
,WEDNESDAY
,THRUSDAY
,FRIDAY
,SATURDAY
FROM
(
    SELECT project_name
    ,personnel_name
    ,DATENAME(dw, report_date) AS day_name
    ,SUM(hours) AS HOURS
    FROM [TimeSheet]

    INNER JOIN [ProjectMaster] 
    ON [TimeSheet].[project_id] = [ProjectMaster].[project_id]

    INNER JOIN [Personnel] 
    ON [TimeSheet].[personnel_id] = [Personnel].[personnel_id]
    WHERE report_date BETWEEN getdate() - 7 AND getdate()
    GROUP BY project_name, personnel_name, DATENAME(dw, report_date)
) sourceQuery PIVOT (SUM(hours) 
 FOR day_name IN 
 (SUNDAY,MONDAY,TUESDAY,WEDNESDAY,THRUSDAY,FRIDAY,SATURDAY)) AS pvt

到目前为止，我将其转换为linq的内容在下面!!!

var before = DateTime.Now.AddDays(-7);
DateTime firstSunday = new DateTime(1753, 1, 7); 

var DayWiseTS = from TSList in objWPFEntities.Timesheets.Include("ProjectMaster").Include("Personnel")
where (TSList.report_date >= before && TSList.report_date <= System.DateTime.Now)
select new { TSList.ProjectMaster.project_name, TSList.Personnel.personnel_name, TSList.report_date, TSList.hours } into sourceQuery
group sourceQuery by new { sourceQuery.project_name, sourceQuery.personnel_name, sourceQuery.report_date, sourceQuery.hours } into pvt
select new 
{ 
projectname = pvt.Key.project_name,
Sunday = (EntityFunctions.DiffDays(firstSunday, pvt.Key.report_date.Value) % 7 == 0 ? pvt.Sum(g => g.hours) : 0),
Monday = (EntityFunctions.DiffDays(firstSunday, pvt.Key.report_date.Value) % 7 == 1 ? pvt.Sum(g => g.hours) : 0),
Tuesday = (EntityFunctions.DiffDays(firstSunday, pvt.Key.report_date.Value) % 7 == 2 ? pvt.Sum(g => g.hours) : 0),
Wednesday = (EntityFunctions.DiffDays(firstSunday, pvt.Key.report_date.Value) % 7 == 3 ? pvt.Sum(g => g.hours) : 0),
Thrusday = (EntityFunctions.DiffDays(firstSunday, pvt.Key.report_date.Value) % 7 == 4 ? pvt.Sum(g => g.hours) : 0),
Friday = (EntityFunctions.DiffDays(firstSunday, pvt.Key.report_date.Value) % 7 == 5 ? pvt.Sum(g => g.hours) : 0),
Saturday = (EntityFunctions.DiffDays(firstSunday, pvt.Key.report_date.Value) % 7 == 6 ? pvt.Sum(g => g.hours) : 0)
};

我在两个查询中都得到了结果，但在sql中，我得到了完美的结果，但是在linq中，我没有得到所需的数据作为sql。

sql result ::

Linq结果::

我想，在我的linq查询中，我没有按小时分组！

任何人都能帮助我吗？

Answer 1

放弃。 EF没有工具集来运行数据透视查询，即使你以某种方式设法执行它，查询的性能也会很糟糕。而不是尝试将SQL查询转换为Linq查询，只需创建具有与查询结果集同名的属性的类：

public class HoursPerDay {
    // if you want different names you must use aliases in your query too
    public string project_name { get; set; } 
    public int SUNDAY { get; set; }
    public int MONDAY { get; set; }
    public int TUESDAY { get; set; }
    public int WEDNESDAY { get; set; }
    public int THURSDAY { get; set; }
    public int FRIDAY { get; set; }
    public int SATURDAY { get; set; }
}

并使用objectContext.ExecuteStoreQuery或dbContext.Database.SqlQuery：

var data = dbContext.Database.SqlQuery<HoursPerDay>(yourSqlQuery);

得出简单的结论：Linq-to-entities最终不会取代SQL。在使用Entity Framework时，SQL仍然是补充工具。

Answer 2

正如拉迪斯拉夫（以及我自己的经验）所说：在一个细分市场中转动比在客户方面做得更有效率。但是你可能有理由不这样做。无论如何，我想我知道问题是什么。您不应该在分组中包含小时数：

group sourceQuery by new { sourceQuery.project_name, sourceQuery.personnel_name,
                           sourceQuery.report_date } into pvt

结果集中的语句保持不变：

...
Sunday = (EntityFunctions.DiffDays(firstSunday, pvt.Key.report_date.Value) % 7
         == 0 ? pvt.Sum(g => g.hours) : 0),