Question

我有2个具有相同列名的表，例如，表A和表B都有列名“Test”。我想从表A和B中选择列Test到实体类。我怎么能这样做？

Answer 1

听起来您希望TableA和TableB的两个实体合并为一个新对象。您可以使用.Select()扩展方法创建新的匿名类型，或者使用已定义的类。

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();

现有班级

 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;
}

如何从Linq中的不同表中选择相同列的名称？

2 个答案: