Question

我必须存储此结果集（示例）：

Author_ID | Author_Name | CoAuthor_ID | Paper_ID | Venue_ID | Year  
------------------------------------------------------------------
677       | Nuno Vascon | 901706      | 812229   | 64309    | 2005
677       | Nuno Vascon | 901706      | 812486   | 65182    | 2005
677       | Nuno Vascon | 901706      | 818273   | 185787   | 2005  
1359      | Peng Shi    | 133112      | 812558   | 65182    | 2005
1359      | Peng Shi    | 266386      | 812558   | 65182    | 2005
1359      | Peng Shi    | 454557      | 812558   | 65182    | 2005  
...       | ...         | ...         | ...      | ...      | ...

在课堂上的对象。即对于相同的Year = 2005，我必须存储不同的Author_ID，Author_Name，CoAuthor_ID，Paper_ID和Venue_ID，这些可以更大数字，而这里只是一个例子。

编辑：

SELECT   AC.Author_ID, A.Author_Name, AC.CoAuthor_ID, AC.Paper_ID, AP.Venue_ID, AC.Year
FROM     AuthorCoAuthor AC
JOIN     AuthorPaper    AP ON AP.Author_ID = AC.Author_ID AND 
                              AP.Paper_ID  = AC.Paper_ID
JOIN     Author         A  ON A.Author_ID  = AC.Author_ID
WHERE    AC.Year = 2005
ORDER BY AC.Author_ID, AC.Year, AC.CoAuthor_ID, AC.Paper_ID, AP.Venue_ID

目的

为了适应这种方法，我问了这个问题。方法如下：

public List<Author> CollectAuthors(int _year)
{
     List<Author> _eAthors = new List<Author>();
     // Get authors from database including all the information in rows for `Author_ID`  
    ...  
    return _eAuthors;  
}

如何将此数据存储在类的对象中？

Answer 1

您可以创建两个单独的类，例如Author：

public class Author
{
     public int Author_ID { get; set; }
     public string Author_Name { get; set; }
     public int Year { get; set; }

     public List<AuthorData> Data { get; set; }
}

和类AuthorData一样：

public class AuthorData
{
    public int CoAuthor_ID { get; set; }
    public int Paper_ID { get; set; }
    public int Venue_ID { get; set; }
}

然后你可以创建这样的实例：

List<Author> authors = new List<Author>();
// assuming you have a SqlCommand "command" executing the query you showed
using (SqlDataReader reader = command.ExecuteReader())
{
    while(reader.Read())
    {
        int author_ID = reader.GetInt(0);
        Author author = authors.FirstOrDefault(a => a.Author_ID == author_ID);
        if (author == null)
        {
            author = new Author{
               Author_ID = author_ID,
               Author_Name = reader.GetString(1),
               Year = reader.GetInt(5),
               Data = new List<AuthorData>()
            };
            authors.Add(author);
        }

        author.Data.Add(new AuthorData{
             CoAuthor_ID = reader.GetInt(2),
             Paper_ID = reader.GetInt(3),
             Venue_ID = reader.GetInt(4)
        });
    }
}

这假设您的ID是Int32而不是Int64，当然您应该添加错误处理。

所以，让我们说你Author中有List<Author>个Authors。然后，您可以选择特定年份的所有public List<Author> AuthorsOfYear(List<Author> fullList, int year) { return fullList.Where(author => author.Year == year).ToList(); }，如下所示：

public List<Author> AuthorsOfYear(List<Author> fullList, int startyear, int endyear)
{
    return fullList.Where(author => 
          author.Year >= startyear && author.Year <= endyear).ToList();
}

和一年的范围：

 exception:bind failed: EACCES (Permission denied)

获取自定义类对象中的值

1 个答案: