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MySQL Query: Selecting rows of linked tables and catching a "bigger" dataset

开发者 https://www.devze.com 2023-03-05 03:37 出处:网络
I am trying to figure out how to build a query, which satisfies the following criteria. I have two tables. Table a stores a list of a开发者_如何学Pythonuthors. And table b stores a list of books. I h

I am trying to figure out how to build a query, which satisfies the following criteria.

I have two tables. Table a stores a list of a开发者_如何学Pythonuthors. And table b stores a list of books. I have a linking table c, which maps every author to one ore more books. Naturally a book can have more then one author. Given a name (let's take name = "Douglas Adams") of an author, I know that if I do

SELECT * FROM linktable
    INNER JOIN a ON linktable.a_id = a.id
    INNER JOIN b ON linktable.p_id = b.id
WHERE a.name = 'Douglas Adams';

I get all the books which were written by Douglas Adams. Let us assume, Douglas Adams sometimes had "coauthors". How do I get them?

I want a list the somehow looks like this:

Douglas Adams, The Hitchhiker's Guide to the Galaxy, maybe more details...
Douglas Adams, Book_2, maybe more details...
Coauthor_1, Book_2, same Details as in "Douglas Adams, Book_2, maybe more details..."

Is this doable?


I have created 3 tables, which map what I want to store and what I want to retrieve.

The 2 storage tables are:

CREATE TABLE `a` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(100) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `name_UNIQUE` (`name`),
  KEY `name_INDEX` (`name`),
  FULLTEXT KEY `name_FULLTEXT` (`name`)
) ENGINE=MyISAM AUTO_INCREMENT=932723 DEFAULT CHARSET=utf8 COLLATE=utf8_bin

CREATE TABLE `b` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `title` varchar(1000) CHARACTER SET utf8 COLLATE utf8_unicode_ci DEFAULT NULL,
  PRIMARY KEY (`id`),
  FULLTEXT KEY `title_fulltext` (`title`)
) ENGINE=MyISAM AUTO_INCREMENT=1617432

and one third table, which links the 2 tables above.

CREATE TABLE `linktable` (
  `a_id` int(11) NOT NULL,
  `b_id` int(11) NOT NULL,
  KEY `a_id_INDEX` (`a_id`),
  KEY `b_id_INDEX` (`b_id`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci


SELECT a2.Name, b.title
    FROM a
        INNER JOIN linktable lt
            ON a.id = lt.a_id
        INNER JOIN b
            ON lt.b_id = b.id
        INNER JOIN linktable lt2
            ON lt.b_id = lt2.b_id
        INNER JOIN a a2
            ON lt2.a_id = a2.id
    WHERE a.Name = 'Douglas Adams'
    ORDER BY b.title,
             /* Case Statement so Douglas Adams sorts before other authors */
             CASE WHEN a2.Name = 'Douglas Adams' THEN 1 ELSE 2 END,
             a2.Name


This should work:

SELECT * FROM b where b.id in(SELECT c.b_id 
FROM a,c
WHERE a.author = "Douglas Adams"
AND a.id= c.a_id)

Edit, Alternative:

SELECT * 
FROM A,B,
(SELECT c.b_id, c.a_id
    FROM a,c
    WHERE a.author = "Douglas Adams"
    AND a.id= c.a_id) X
WHERE b.id = x.b_id
    AND a.id = x.a_id
0

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