MySQL使用ascii版本匹配unicode字符

Question

我正在运行MySQL 5.1.50并且有一个如下所示的表:

organizations | CREATE TABLE `organizations` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` text CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL,
  `url` text CHARACTER SET utf8 COLLATE utf8_unicode_ci DEFAULT NULL,
  `phone` varchar(20) CHARACTER SET utf8 COLLATE utf8_unicode_ci DEFAULT NULL,
  `timestamp` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`),
  KEY `id` (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=25837 DEFAULT CHARSET=utf8 |

我遇到的问题是MySQL将unicode字符与ascii版本匹配.例如,当我搜索包含"é"的单词时,它将匹配具有"e"的相同单词,反之亦然:

mysql> SET NAMES utf8;
Query OK, 0 rows affected (0.00 sec)

mysql> SELECT id, name FROM `organizations` WHERE `name` = 'Universite de Montreal';
    +-------+-------------------------+
| id    | name                    |
+-------+-------------------------+
| 16973 | Université de Montreal  |
+-------+-------------------------+
1 row in set (0.01 sec)

我从PHP和命令行控制台获得了这些结果.如何从SELECT查询中获得准确的匹配？

谢谢!

Answer 1

您指定了name列text CHARACTER SET utf8 COLLATE utf8_unicode_ci,告诉MySQL 在匹配和排序时将e和é视为等效.整理并且utf8_general_ci两者都有很多相同的东西.

http://www.collat​​ion-charts.org/是一个很好的资源,一旦你学会了如何阅读图表,这是非常容易的.

如果您希望e和é等被认为不同,那么您必须选择不同的排序规则.要找出服务器上的排序规则(假设您仅限于UTF-8编码):

mysql> show collation like 'utf8%';

并选择使用整理图表作为参考.

另一个特殊的校对是utf8_bin没有等价的,它是二元匹配.

我所知道的唯一不是语言特定的MySQL Unicode排序规则是utf8_unicode_ci,utf8_general_ci和utf8_bin.他们很奇怪.整理的真正目的是使计算机与某个人所期望的人匹配和排序.匈牙利语和土耳其语词典根据不同的规则排序.指定排序规则允许您根据此类本地规则进行排序和匹配.

例如,似乎丹麦人认为e和é等价,但冰岛人不这样做:

mysql> select _utf8'e' collate utf8_danish_ci
    -> = _utf8'é' collate utf8_danish_ci as equal;
+-------+
| equal |
+-------+
|     1 |
+-------+

mysql> select _utf8'e' collate utf8_icelandic_ci
    -> = _utf8'é' collate utf8_icelandic_ci as equal;
+-------+
| equal |
+-------+
|     0 |
+-------+

另一个方便的技巧是用一堆你感兴趣的字符填充一个列表(从脚本中更容易)然后MySQL可以告诉你等价:

mysql> create table t (c char(1) character set utf8);
mysql> insert into t values ('a'), ('ä'), ('á');
mysql> select group_concat(c) from t group by c collate utf8_icelandic_ci;
+-----------------+
| group_concat(c) |
+-----------------+
| a               |
| á               |
| ä               |
+-----------------+

mysql> select group_concat(c) from t group by c collate utf8_danish_ci;
+-----------------+
| group_concat(c) |
+-----------------+
| a,á             |
| ä               |
+-----------------+

mysql> select group_concat(c) from t group by c collate utf8_general_ci;
+-----------------+
| group_concat(c) |
+-----------------+
| a,ä,á           |
+-----------------+

Answer 2

当然,这将有效:

SELECT * FROM table WHERE name LIKE BINARY 'namé';