Question

目前，我有一个程序可以对一系列书籍进行排序＆amp;作者。现在，它是由按标题分组的作者输出，这意味着它打印作者的姓名＆amp;他/她写的所有书。好吧，我正试图扭转那个＆amp;按书本输出，＆amp;然后是所有撰写该书的作者。很多人会非常感激。

// get authors and titles of each book
        // they co-authored; group by author
        var titlesByAuthor =
            from author in dbcontext.Authors
            orderby author.LastName, author.FirstName
            select new
            {
                Name = author.FirstName + " " + author.LastName,
                Titles =
                from book in author.Titles
                orderby book.Title1
                select book.Title1
            };

        outputTextBox.AppendText("\r\n\r\nTitles grouped by author:");

        // display titles written by each author, grouped by author
        foreach (var author in titlesByAuthor)
        {
            //display author's name
            outputTextBox.AppendText("\r\n\t" + author.Name + ":");
            // display titles written by that author
            foreach (var title in author.Titles)
            {
                outputTextBox.AppendText("\r\n\t\t" + title);
            }
        }

Answer 1

请使用linq group by operator按书籍分组。这是一个示例：

public void Linq40() 
{ 
    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 }; 

    var numberGroups = 
        from n in numbers 
        group n by n % 5 into g 
        select new { Remainder = g.Key, Numbers = g }; 

    foreach (var g in numberGroups) 
    { 
        Console.WriteLine("Numbers with a remainder of {0} when divided by 5:", g.Remainder); 
        foreach (var n in g.Numbers) 
        { 
            Console.WriteLine(n); 
        } 
    } 
}

Answer 2

以下查询将为您提供所需内容：

var booksByAuthor =
    from book in dbcontext.Books
    orderby book.Title1
    select new
    {
        Authors = 
            from a in book.Authors
            orderby a.LastName, a.FirstName
            select a.FirstName + " " + a.LastName
        Titles = book.Title1
    };

你应该能够自己弄清楚其他部分。

<强>更新

foreach (var book in booksByAuthor)
{
    //display book's title
    outputTextBox.AppendText("\r\n\t" + book.Title1 + ":");

    // display authors of that book
    foreach (var author in book.Authors)
    {
        outputTextBox.AppendText("\r\n\t\t" + author);
    }
}

LINQ排序，按作者分组的标题

2 个答案: