将 SQL Rank() 转换为 LINQ 或替代方法 [英] Converting SQL Rank() to LINQ, or alternative

问题描述

我有以下 SQL 语句，可以按需要/预期工作.但是我想将它翻译成 LINQ 语句(Lambda??)，以便它适合我的 DAL 的其余部分.但是我无法弄清楚如何在 LINQ 中模拟 Rank().

I have the below SQL statement that works as desired/expected. However I would like to translate it into a LINQ statement(Lambda??) so that it will fit with the rest of my DAL. However I cannot see to figure out how to simulate Rank() in LINQ.

我在这里发布它的原因(可能是错误的)是为了看看是否有人可以替代 Rank() 语句，以便我可以将其转换.或者，如果有一种在 LINQ 中表示 Rank() 的方法，那也将不胜感激.

The reason I posted it here, which is maybe in error, is to see if anyone has an alternative to the Rank() statement so that I can get this switched over. Alternatively, if there is a way to represent Rank() in LINQ that would be appreciated also.

USE CMO

SELECT      vp.[PersonID] AS [PersonId]
            ,ce.[EnrollmentID]
            ,vp.[FirstName]
            ,vp.[LastName]
            ,ce.[EnrollmentDate]
            ,ce.[DisenrollmentDate]
            ,wh.WorkerCategory

FROM  [dbo].[vwPersonInfo] AS vp
            INNER JOIN 
            (
                  [dbo].[tblCMOEnrollment] AS ce
                  LEFT OUTER JOIN
                        (
                              SELECT   *
                                          ,RANK()OVER(PARTITION BY EnrollmentID ORDER BY CASE WHEN EndDate IS NULL THEN 1 ELSE 2 END, EndDate DESC, StartDate DESC) AS whrank 
                              FROM  [dbo].[tblWorkerHistory]
                              WHERE WorkerCategory = 2
                        ) AS wh 
                              ON ce.[EnrollmentID] = wh.[EnrollmentID] AND wh.whrank = 1
            ) 
                  ON vp.[PersonID] = ce.[ClientID]

WHERE (vp.LastName NOT IN ('Client','Orientation','Real','Training','Matrix','Second','Not'))
AND (
            (wh.[EndDate] <= GETDATE())
            OR wh.WorkerCategory IS NULL
      ) 
AND (
            (ce.[DisenrollmentDate] IS NULL) 
            OR (ce.[DisenrollmentDate] >= GetDate())
      )

推荐答案

下面的示例展示了我如何在 Linq 中模拟 Rank():

Here's a sample that shows how I would simulate Rank() in Linq:

var items = new[]
{
    new { Name = "1", Value = 2 },
    new { Name = "2", Value = 2 },
    new { Name = "3", Value = 1 },
    new { Name = "4", Value = 1 },
    new { Name = "5", Value = 3 },
    new { Name = "6", Value = 3 },
    new { Name = "7", Value = 4 },
};
  
var q = from s in items
    orderby s.Value descending
    select new 
    { 
        Name = s.Name, 
        Value = s.Value,
        Rank = (from o in items
                where o.Value > s.Value
                select o).Count() + 1 
    };

foreach(var item in q)
{
    Console.WriteLine($"Name: {item.Name} Value: {item.Value} Rank: {item.Rank}");
}

输出

Name: 7 Value: 4 Rank: 1
Name: 5 Value: 3 Rank: 2
Name: 6 Value: 3 Rank: 2
Name: 1 Value: 2 Rank: 4
Name: 2 Value: 2 Rank: 4
Name: 3 Value: 1 Rank: 6
Name: 4 Value: 1 Rank: 6

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