Question

ID  UserName    BookType    bookID

1   Krish   1   1
1   Krish   1   2
1   Krish   2   1
1   Krish   2   2
2   Ram     1   1    
3   Raj     1   1
3   Raj     1   2

我有上面的表格，我希望为每个用户获取不同的booktype计数和bokkID计数，我能够在sqlserver中写这个，但是当我来到LINQ时无法编写查询。

我需要以下输出，

ID  UserName    BookType    bookID

1   Krish   2   2
2   Ram     1   1 
3   Raj     1   2

Answer 1

这应该给你正确的结果： -

var result = Userlist.GroupBy(x => new { x.ID, x.UserName })
                     .Select(x => new
                                 {
                                     ID = x.Key.ID,
                                     UserName = x.Key.UserName,
                                     BookType = x.Max(z => z.BookType),
                                     BookId = x.Max(z => z.BookId)
                                 });

<强>更新

虽然您同意回答，但我错过了您的要求，上面发布的答案是错误的，因为它获取了最大的BookType＆amp; BOOKID。以下是获取非重复计数的查询： -

var result = Userlist.GroupBy(x => new { x.ID, x.UserName })
                     .Select(x => new
                         {
                            ID = x.Key.ID,
                            UserName = x.Key.UserName,
                            BookType = x.Select(z => z.BookType).Distinct().Count(),
                            BookId = x.Select(z => z.BookId).Distinct().Count()
                         });

与Linq中的群组不同

1 个答案: