c# - 如何在 Linq 中进行 Pivot

Question

可能重复：
我怎样才能为此做一个支点

我有一个如下提供的表格

 ID     |     value     |    Name
--------+---------------+------------------
  1           Digital        Model
  1           companyA       Manufacturer
  2           Analog         Model
  2           CompanyB       Manufacturer
  3           Fiber          Model
  3           CompanyC       Manufacturer

I need to convert this back to 

 ID     |     Model    |     Manufacturer
--------+--------------+-------------------
 1           Digital          companyA           
 2           Analog           CompanyB        
 3            Fiber           CompanyC       

请帮助我解决这个问题。使用 T-SQL，我能够正确转换它。但是，使用 Linq，我发现编写 Query 有问题。

Answer 1

试试这个：

 var results = Data.GroupBy(l => l.Name);
            .SelectMany( g => 
                         new 
                         { 
                             Metadata = g.Key, 
                             data = g 
                         });
var pivoted = new List<PivotedEntity>();

foreach(var item in results)
{
    pivoted.Add( 
        new PivotedEntity
        {
            Id  = item.Id,
            Model = item.data.Where(x => x.Name == "Model")
                        .FirstOrDefault().value,
            Manufacturer = item.data.Where(x => x.Name == "Manufacturer")
                         .FirstOrDefault().value,
        });
}

您应该首先定义一个新类：

public class PivotedEntity
{
    public int Id {get; set;}
    public string Model {get; set;}
    public string Manufacturer {get; set;}   
}