实体框架查询嵌套查询 [英] Entity Framework Query Nested Query

问题描述

我是实体框架的新手，正在尝试将以下查询转换为正确的函数调用。

I am new to the entity framework and am trying to convert the following query into the correct function calls.

Select Distinct a.nodeId FROM 
    (SELECT *
    FROM reportContents
    Where fitId = '29' and reportId = 
       (select max(reportId) 
       from reportContents
       where fitId = '29')
     ) a Where (a.nodeId IS NOT NULL)

我知道此查询可以实现我想要的功能，但是我不确定如何将其转换为实体框架！

I know this query does what i want, however i'm not sure how to translate that into the entitiy framework!

这是我的尝试。

var prevSelectedNodes = db.reportContents.Where(
f => f.fitId == id).Select(
f => f.nodeId).Distinct().ToList();

我需要以某种方式将.Select（）放在where调用中。但是，这种事情似乎不太可能

I need to somehow put a .Select() in the where call. However that kind of thing dosen't seem possible

预先感谢您！

推荐答案

因为您不能创建两个LINQ嵌套的lambda表达式。您可以通过两个请求来做到这一点：

As you can't make two LINQ nested lambda expression. You can do it with two requests :

var maxReportId = db.reportContents.Where(r => r.fitId = "29").Max(r => r.RepordId);
var result = db.reportContents.Where(r => r.fitId == "29" && r.reportId == maxReportId && r.nodeId != null).Select(a => a.nodeId).Distinct().ToList() ; 

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