如何从Linq中的不同表中选择同一列的名称？

Question

我有2个表具有相同的列名称，例如，表A和表B都有列的名称“测试”。我想从表A和B中选择列Test到实体类。我怎样才能做到这一点？

Answer 1

这听起来像你希望TableA和TableB的两个实体合并成一个新的对象。您可以使用.Select()扩展方法创建一个新的匿名类型，或者创建一个您已经定义的类。

这里的要求是你必须在TableA和TableB之间找到一个共同的属性。在这里，我假设你有类似ID的东西来匹配它们。

匿名类型

var mergedTests = from a in db.TableA 
        join b in db.TableB on a.CommonID equals b.CommonID 
        select new 
          { TestFromA = a.Test, TestFromB = b.Test } 
        .ToList(); 

现有类

List<MyCustomTests> mergedTests = from a in db.TableA 
        join b in db.TableB on a.CommonID equals b.CommonID 
        select new MyCustomTests 
         { TestName= a.Test, ShortName= b.Test } 
        .ToList(); 

Answer 2

class Program 
{ 
    static void Main(string[] args) 
    { 
     var A = new Data[] { 
      new Data { Test = 1, Relation = 1 }, 
      new Data { Test = 2, Relation = 2 }, 
      new Data { Test = 3, Relation = 3 }, 
      new Data { Test = 4, Relation = 4 }, 
      new Data { Test = 5, Relation = 5 }, 
     }; 

     var B = new Data[] { 
      new Data { Test = 2, Relation = 2 }, 
      new Data { Test = 3, Relation = 3 }, 
      new Data { Test = 5, Relation = 5 }, 
     }; 

     var res = from a in A 
        join b in B on a.Relation equals b.Relation 
        select new { TestA = a.Test, TestB = b.Test }; 
    } 
} 

class Data 
{ 
    public int Test; 
    public int Relation; 
}