linq连接问题

发布于 2024-10-21 02:10:05 字数 609 浏览 1 评论 0原文

假设我们有两个这样的表：

table1

|   date   | data1 |
| 3/2/2011 |  xyz  |
| 3/4/2011 |  abc  |

table2

|  date    |  data2  |  data3  |
| 3/2/2011 |  def    |   ghi   |
| 3/9/2011 |  jkl    |   mno   |

我们如何编写一个连接来获取

|日期 |数据1 |数据2 |数据3 |

假设我们的 MyModel 定义如下：

MyModel{
  public DateTime TheDate {get;set;}
  public int Data1 {get;set;}
  public int Data2 {get;set;}
  public int Data3 {get;set;}
}

我知道我们必须使用 DefaultIfEmpty，但我不知道当没有相应的日期行（如两个表的第 2 行中）时如何合并两者。

感谢您的任何想法。

原文

Suppose we have two tables like this:

table1

|   date   | data1 |
| 3/2/2011 |  xyz  |
| 3/4/2011 |  abc  |

table2

|  date    |  data2  |  data3  |
| 3/2/2011 |  def    |   ghi   |
| 3/9/2011 |  jkl    |   mno   |

How do we write a join to get

Let's say we have MyModel defined like this:

MyModel{
  public DateTime TheDate {get;set;}
  public int Data1 {get;set;}
  public int Data2 {get;set;}
  public int Data3 {get;set;}
}

I know we have to use DefaultIfEmpty but I don't know how to merge the two when there's no corresponding date line like in row 2 of both tables.

Thanks for any ideas.

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手长情犹 2024-10-28 02:10:05

var results = from t1 in table1
              let t2 = (from t in table2 select t)
              where t1.date == t2.date
              select new MyModel {
                TheDate = t1.date == null ? t2.date : t1.date,
                Data1 = t1.data1,
                Data2 = t2.data2,
                Data3 = t2.data3
              };

var results = from t1 in table1
              let t2 = (from t in table2 select t)
              where t1.date == t2.date
              select new MyModel {
                TheDate = t1.date == null ? t2.date : t1.date,
                Data1 = t1.data1,
                Data2 = t2.data2,
                Data3 = t2.data3
              };

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