在Linq分组，排名和前10名 [英] Group by, Order by and top 10 in Linq

问题描述

如何从列表中获得前十大保险金额请帮助。我试过这种方式，但它没有用。

公共类Top10Insurance 
 {
 public string Amt {get ;组; } 
} 
 
列表< Top10Insurance> result = InfoDB 
 .GroupBy（a => a.InsuranceName）
。选择（b => new Top10Insurance 
 {
 Amt = b.Sum（c => c.BalanceAmount）.ToString（），
}）。OrderByDescending（d => d.Amt）.Take（10）。ToList（）; 

解决方案

OP回答！

Mohammed_Faisal [ ^ ]在评论中写道：

当我转换时：

< pre lang =c＃> public class Top10Insurance
{
public double Amt { get ; set ; }
}

Amt = b.Sum（c = > c.BalanceAmount）

i出现此错误：

< br /> 
无法将类型'decimal？'隐式转换为'double'。存在显式转换（你是否错过演员？）

他回答了自己的问题：

 Amt =（ double ）b.Sum（c = >  c.BalanceAmount）

How do i get the top 10 Insurance Amount from the List please help. I have tried in this way but its not working.

 public class Top10Insurance
    {        
        public string Amt { get; set; }        
    }

List<Top10Insurance> result = InfoDB
                 .GroupBy(a => a.InsuranceName)
                 .Select(b => new Top10Insurance
                 {
                    Amt = b.Sum(c => c.BalanceAmount).ToString(),
                 }).OrderByDescending(d => d.Amt).Take(10).ToList();

解决方案

Answered by OP!

Mohammed_Faisal[^] wrote in the comment to the question:

When i converted :

public class Top10Insurance
{
public double Amt { get; set; }
}

Amt = b.Sum(c => c.BalanceAmount)

i got this error:

<br />
Cannot implicitly convert type 'decimal?' to 'double'. An explicit conversion exists (are you missing a cast?)

And he answered his own question:

Amt = (double)b.Sum(c => c.BalanceAmount)

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