MySQL 通过关系过滤查询

Question

我在 2 个有关系的 MySQL 表上遇到以下问题： 当我想要完整列表或按姓名或电子邮件等过滤结果时，我可以轻松查询表 1（地址）。但现在我需要查询表1并根据表2的关系内容（兴趣）对其进行过滤。因此，仅当表 2 中满足一个（或多个）条件时，我才需要在表 1 中查找一行（通常是许多行）。

以下是表格：

CREATE TABLE IF NOT EXISTS `address` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(100) COLLATE utf8_unicode_ci NOT NULL,
  `email` varchar(100) COLLATE utf8_unicode_ci NOT NULL,
  `countryCode` char(2) COLLATE utf8_unicode_ci DEFAULT NULL,
  `languageCode` char(2) COLLATE utf8_unicode_ci DEFAULT NULL,
  `timestamp` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`),
  UNIQUE KEY `emailUnique` (`email`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci

INSERT INTO `address` (`id`, `name`, `email`, `countryCode`, `languageCode`, `timestamp`) VALUES
(1, '', '[email protected]', 'BE', 'nl', '2010-07-16 14:07:00'),
(2, '', '[email protected]', 'BE', 'fr', '2010-07-16 14:10:25');

CREATE TABLE IF NOT EXISTS `interests` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `address_id` int(11) unsigned NOT NULL,
  `cat` char(2) COLLATE utf8_unicode_ci NOT NULL,
  `subcat` char(2) COLLATE utf8_unicode_ci NOT NULL,
  `timestamp` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`),
  KEY `address_id` (`address_id`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci

INSERT INTO `interests` (`id`, `address_id`, `cat`, `subcat`, `timestamp`) VALUES
(1, 1, 'aa', 'xx', '2010-07-16 14:07:00'),
(2, 1, 'aa', 'yy', '2010-07-16 14:07:00'),
(3, 2, 'aa', 'xx', '2010-07-16 14:07:00'),
(4, 2, 'bb', 'zz', '2010-07-16 14:07:00')
(5, 2, 'aa', 'yy', '2010-07-16 14:07:00');

ALTER TABLE `interests`
  ADD CONSTRAINT `interests_ibfk_1` FOREIGN KEY (`address_id`) REFERENCES `address` (`id`) ON DELETE CASCADE ON UPDATE NO ACTION;

例如，我需要查找具有 (有）作为兴趣 cat=aa 和 subcat=xx。或者，另一个例子，我需要同时感兴趣的地址 cat=aa 和 subcat=xx 以及 cat=aa 和 subcat=yy。特别是后者很重要，必须记住，地址和兴趣表都将是很长的列表，并且目录/子目录组合的数量会有所不同。我目前正在通过 Zend_Db_Table (findDependentRowset) 处理参考查询，但该解决方案对于命中数为 100 甚至 1000 的地址列表来说会减慢速度。

感谢您的帮助。

Answer 1

SELECT a.name FROM address a
INNER JOIN interests i ON (a.id = i.address_id)
WHERE i.cat = "aa" AND i.subcat IN ('xx', 'yy')

Answer 2

我在您的兴趣表中添加了另一行，以演示两个示例之间不同的结果集：

INSERT INTO interests VALUES (6, 2, 'aa', 'vv', '2010-07-16 14:07:00');

然后您可能需要尝试使用相关子查询，如下所示：

SELECT * 
FROM   address a 
WHERE  EXISTS (SELECT id 
               FROM   interests 
               WHERE  address_id = a.id AND 
                      (cat = 'aa' and subcat = 'xx'));

结果：

+----+------+--------------------+-------------+--------------+---------------------+
| id | name | email              | countryCode | languageCode | timestamp           |
+----+------+--------------------+-------------+--------------+---------------------+
|  1 |      | [email protected]     | BE          | nl           | 2010-07-16 14:07:00 |
|  2 |      | [email protected] | BE          | fr           | 2010-07-16 14:10:25 |
+----+------+--------------------+-------------+--------------+---------------------+
2 rows in set (0.00 sec)

对于第二个示例，我们正在测试之前添加的新行为了不得到与上面相同的结果：

SELECT * 
FROM   address a 
WHERE  EXISTS (SELECT id 
               FROM   interests 
               WHERE  address_id = a.id AND 
                      (cat = 'aa' and subcat = 'xx')) AND
       EXISTS (SELECT id 
               FROM   interests 
               WHERE  address_id = a.id AND 
                      (cat = 'aa' and subcat = 'vv'));

结果：

+----+------+--------------------+-------------+--------------+---------------------+
| id | name | email              | countryCode | languageCode | timestamp           |
+----+------+--------------------+-------------+--------------+---------------------+
|  2 |      | [email protected] | BE          | fr           | 2010-07-16 14:10:25 |
+----+------+--------------------+-------------+--------------+---------------------+
1 row in set (0.00 sec)

使用相关子查询简单明了。但请记住，就性能而言，它可能不是最好的，因为相关子查询将为外部查询中的每个地址执行一次。