Question

我有2张表，其中一张：

相册：

CREATE TABLE IF NOT EXISTS `albums` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(64) NOT NULL,
  `singer` varchar(64) NOT NULL,
  `year` int(11) NOT NULL,
  `releaseDate` date DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `categoryId` (`categoryId`),
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 AUTO_INCREMENT=7 ;

音乐：

CREATE TABLE IF NOT EXISTS `musics` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(128) NOT NULL,
  `singer` varchar(128) NOT NULL,
  `genre` varchar(128) NOT NULL,
  `albumId` int(11) DEFAULT NULL,
  `year` int(4) NOT NULL,
  `releaseDate` date DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `categoryId` (`categoryId`),
  KEY `albumId` (`albumId`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 AUTO_INCREMENT=16 ;

我想加入那个表并按releaseDate排序。这是可能的？抱歉我的英文。

结果： 现在我得到了一些结果：

+-----------------------------------------------+-------------------------+-------------+
| albums_name                                   | musics_name             | releaseDate |
+-----------------------------------------------+-------------------------+-------------+
| The Artificial Theory For The Dramatic Beauty | K                       | NULL        |
| The Artificial Theory For The Dramatic Beauty | Fiction In Hope         | NULL        |
| The Artificial Theory For The Dramatic Beauty | Chemicarium             | NULL        |
| The Artificial Theory For The Dramatic Beauty | Voice                   | NULL        |
| The Artificial Theory For The Dramatic Beauty | Blue                    | NULL        |
| The Artificial Theory For The Dramatic Beauty | Mirror                  | NULL        |
| The Artificial Theory For The Dramatic Beauty | If You Want To Wake Up? | NULL        |
| The Artificial Theory For The Dramatic Beauty | Interlude               | NULL        |
| NULL                                          | Everything At Once      | 2010-11-11  |
| NULL                                          | Blue Freightliner       | 2011-11-11  |
+-----------------------------------------------+-------------------------+-------------+

我想：

+-----------------------------------------------+-------------------------+-------------+
| albums_name                                   | musics_name             | releaseDate |
+-----------------------------------------------+-------------------------+-------------+
| The Artificial Theory For The Dramatic Beauty | NULL                    | 2009-11-11  |
| NULL                                          | Everything At Once      | 2010-11-11  |
| NULL                                          | Blue Freightliner       | 2011-11-11  |
+-----------------------------------------------+-------------------------+-------------+

Answer 1

你应该学习/玩JOIN。有几种不同的类型（INNER JOIN，LEFT JOIN）。

这是一个让你入门的简单例子：

SELECT albums.name AS albums.name, musics.name AS musics_name, musics.releaseDate 
    FROM albums 
    LEFT JOIN musics ON albums.id = musics.albumId 
    ORDER BY musics.releaseDate

或者，如果你需要音乐，只有匹配的专辑：

SELECT albums.name AS albums.name, musics.name AS musics_name, musics.releaseDate 
    FROM musics 
    LEFT JOIN albums ON musics.albumId = albums.id
    ORDER BY musics.releaseDate

Answer 2

您的输出有两个截然不同的部分：

相册及其发布日期;
无专辑曲目及其发布日期。

每个部分来自不同的表格，这对我来说是一个典型的 union 示例，而不是两个集合的连接：

SELECT
  name AS albums_name,
  NULL AS musics_name,
  releaseDate
FROM albums

UNION ALL

SELECT
  NULL AS albums_name,
  name AS musics_name,
  releaseDate
FROM musics
WHERE
  album_id IS NULL

ORDER BY
  releaseDate ASC
;

两个不同的表连接mysql

2 个答案: