Question

我在MySQL数据库中有一个包含Title和Author列的书籍表。我需要选择所有书籍中包含超过X本书的作者的书籍。

以下是所需输出的示例：

| Author        | Title                |
|---------------|----------------------|
| Dan Brown     | Angels and Demons    |
| Dan Brown     | The Da Vinci Code    |
| Robert Ludlum | The Bourne Identity  |
| Robert Ludlum | The Bourne Supremacy |

每个作者可以使用一个简单的小组获得一本书并具有条件：

SELECT * FROM books
GROUP BY author
HAVING count(author) > 1
ORDER BY author;

其中给出了以下输出：

| Author        | Title                |
|---------------|----------------------|
| Dan Brown     | Angels and Demons    |
| Robert Ludlum | The Bourne Identity  |

如何获得一本包含超过X本书的作者的书籍列表？

Answer 1

您可以将查询用作sub-select：

SELECT * FROM books WHERE Author IN (
    SELECT Author
    FROM books
    GROUP BY Author
    HAVING COUNT(Author) > 1
) ORDER BY Author, Title;

如果您想获得每位作者的简单（逗号分隔）书籍列表，您还可以使用GROUP_CONCAT使用以下解决方案：

SELECT Author, GROUP_CONCAT(Title) AS title_list
FROM books
GROUP BY Author
HAVING COUNT(Author) > 1
ORDER BY Author;

演示： http://sqlfiddle.com/#!9/10d80f/2/0

Answer 2

您应该可以使用subquery：

SELECT * FROM books
WHERE author IN (
  SELECT author
    FROM books
    GROUP BY author
    HAVING COUNT(author) > 1
  )

Answer 3

也许尝试使用in ...

SELECT [Author] , [Title]
  FROM [books] b
  where [Author] in 
  (select Author from [books] group by [Author]
       having count(Author) >1)

Answer 4

一个非常简单的查询将如下所示

SELECT books.Title
FROM (SELECT Count(books.Author) AS CountOfAuthor, books.Author AS A
FROM books
GROUP BY books.Author )  AS bookByAuthor INNER JOIN books ON bookByAuthor.A = 
books.Author
WHERE (((books.Author)=[bookByAuthor].[A]));

希望这会有所帮助

获取列值超过X条目的所有行

4 个答案: