Linq 中的 Row_number 超过(按 xxx 分区)? [英] Row_number over (Partition by xxx) in Linq?

问题描述

我有一个DataTable，它有一个结构和数据:

I have a DataTable which has a structure and data:

id |   inst   |   name
------------------------
 1 |  guitar  |  john
 2 |  guitar  |  george
 3 |  guitar  |  paul
 4 |  drums   |  ringo
 5 |  drums   |  pete

我可以通过以下方式检索记录:

I can retrieve the records via:

IEnumerable <Beatle>...

class Beatle
{
  int id;
  string inst;
  string name;
}

我想了解演奏不同乐器的人的内部顺序.在 MSSQL 中我会使用

I'd like to get the internal order of those who play the different instruments. In MSSQL I'd use

SELECT 
    *
    ,Row_Number() OVER (PARTITION BY inst ORDER BY id) AS rn
FROM Beatles

此查询返回

id |   inst   |   name  | rn
-----------------------------
 1 |  guitar  |  john   | 1
 2 |  guitar  |  george | 2
 3 |  guitar  |  paul   | 3
 4 |  drums   |  ringo  | 1
 5 |  drums   |  pete   | 2

问题:
我怎样才能在 Linq 中做到这一点?

推荐答案

B"H

我知道这是旧的.但为什么解决方案不简单?

I know this is old. But why isn't the solution simply?

var o = beatles.GroupBy(x => x.inst)
               .SelectMany(g =>
                   g.Select((j, i) => new { j.inst, j.name, rn = i + 1 })
               );

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