Question

我遇到一个问题，我有一个表Book与BookByEditor表的多对多关系，这个表与Editor表具有相同的关系，这个想法是一本书可能有很多编辑，编辑可能会有很多书。

这里快速了解我的表格：

public partial class Book
{
    public int BookID { get; set; }
    public string BookName { get; set; }
    (...)

    public virtual ICollection<BookByEditor> BookByEditor { get; set; }
}


public partial class BookByEditor
{
    public int BookByEditorId { get; set; }
    public int BookID { get; set; }
    public int EditorID { get; set; }

    public virtual Book Book { get; set; }
    public virtual Editor Editor { get; set; }
}


public partial class Editor
{
    public int EditorID { get; set; }
    public string EditorName { get; set; }
    (...)

    public virtual ICollection<BookByEditor> BookByEditor { get; set; }
}

所以我喜欢的是，例如，能够进行查询以获得所有书籍按编辑按字母顺序排序;意思是编辑A，编辑B，编辑C等。我希望我对自己所寻求的内容足够清楚。

我正在使用linq来实现sql和linqkit，所以任何方法都可以。

通常我会这样做：

IQueryable<Editor> editors = from e in context.Editor.OrderBy(x => x.EditorName)
                                                         select e;

                            List<Editor> listEditors = new List<Editor>
                                {
                                    editors.First()
                                };

                            count = 0;

                            Editor editorModel = listEditors.Last();

                            while (listBook.Count < 20)
                            {
                                IQueryable<Book> bookByEditor =
                                    from e in context.Book.Where(
                                        item => item.BookByEditor.Any(x => x.EditorID == editorModel.EditorID))
                                    select e;

                                switch (secondOption)
                                {
                                    default:
                                        fetch = bookByEditor.OrderBy(x => x.BookID).Skip(pageCount * 20).Take(20).ToList();
                                        break;
                                    case "New":
                                        fetch = bookByEditor.OrderByDescending(x => x.DateAdded).Skip(pageCount * 20).Take(20).ToList();
                                        break;
                                    case "Old":
                                        fetch = bookByEditor.OrderBy(x => x.DateAdded).Skip(pageCount * 20).Take(20).ToList();
                                        break;
                                }

                                listBook.AddRange(fetch);

                                count++;

                                listEditors.AddRange(editors.Skip(count).Take(1));

                                editorModel = listEditors.Last();
                            }

但我对这种方法不满意，我不确定结果......

Answer 1

如何通过编辑器对书籍进行分组，然后对其进行排序。选择多少来取回书籍？

在表上订购具有多对多关系的查询

1 个答案: