mysql字符集与校对规则
mysql字符集与校对规则
mysql的字符集和校对规则有四个级别的默认设置：服务器级，数据库级，表级和字段级。他们分别在不同的地方设置，作用也不同。
查看字符集级对应的校对规则。
Charset：字符集，Default collation：默认使用的校对规则。Maxlen：字符集的最大长度
mysql> show character set;
+----------+---------------------------------+---------------------+--------+
| Charset | Description | Default collation | Maxlen |
+----------+---------------------------------+---------------------+--------+
| armscii8 | ARMSCII-8 Armenian | armscii8_general_ci | 1 |
| ascii | US ASCII | ascii_general_ci | 1 |
| big5 | Big5 Traditional Chinese | big5_chinese_ci | 2 |
| binary | Binary pseudo charset | binary | 1 |
| cp1250 | Windows Central European | cp1250_general_ci | 1 |
| cp1251 | Windows Cyrillic | cp1251_general_ci | 1 |
| cp1256 | Windows Arabic | cp1256_general_ci | 1 |
| cp1257 | Windows Baltic | cp1257_general_ci | 1 |
| cp850 | DOS West European | cp850_general_ci | 1 |
| cp852 | DOS Central European | cp852_general_ci | 1 |
| cp866 | DOS Russian | cp866_general_ci | 1 |
| cp932 | SJIS for Windows Japanese | cp932_japanese_ci | 2 |
| dec8 | DEC West European | dec8_swedish_ci | 1 |
| eucjpms | UJIS for Windows Japanese | eucjpms_japanese_ci | 3 |
| euckr | EUC-KR Korean | euckr_korean_ci | 2 |
| gb18030 | China National Standard GB18030 | gb18030_chinese_ci | 4 |
| gb2312 | GB2312 Simplified Chinese | gb2312_chinese_ci | 2 |
| gbk | GBK Simplified Chinese | gbk_chinese_ci | 2 |
| geostd8 | GEOSTD8 Georgian | geostd8_general_ci | 1 |
| greek | ISO 8859-7 Greek | greek_general_ci | 1 |
| hebrew | ISO 8859-8 Hebrew | hebrew_general_ci | 1 |
| hp8 | HP West European | hp8_english_ci | 1 |
| keybcs2 | DOS Kamenicky Czech-Slovak | keybcs2_general_ci | 1 |
| koi8r | KOI8-R Relcom Russian | koi8r_general_ci | 1 |
| koi8u | KOI8-U Ukrainian | koi8u_general_ci | 1 |
| latin1 | cp1252 West European | latin1_swedish_ci | 1 |
| latin2 | ISO 8859-2 Central European | latin2_general_ci | 1 |
| latin5 | ISO 8859-9 Turkish | latin5_turkish_ci | 1 |
| latin7 | ISO 8859-13 Baltic | latin7_general_ci | 1 |
| macce | Mac Central European | macce_general_ci | 1 |
| macroman | Mac West European | macroman_general_ci | 1 |
| sjis | Shift-JIS Japanese | sjis_japanese_ci | 2 |
| swe7 | 7bit Swedish | swe7_swedish_ci | 1 |
| tis620 | TIS620 Thai | tis620_thai_ci | 1 |
| ucs2 | UCS-2 Unicode | ucs2_general_ci | 2 |
| ujis | EUC-JP Japanese | ujis_japanese_ci | 3 |
| utf16 | UTF-16 Unicode | utf16_general_ci | 4 |
| utf16le | UTF-16LE Unicode | utf16le_general_ci | 4 |
| utf32 | UTF-32 Unicode | utf32_general_ci | 4 |
| utf8 | UTF-8 Unicode | utf8_general_ci | 3 |
| utf8mb4 | UTF-8 Unicode | utf8mb4_0900_ai_ci | 4 |
+----------+---------------------------------+---------------------+--------+
41 rows in set (0.04 sec)
可通过命令查看字符集对应的可用的校对规则。
mysql> show collation like 'gbk%';
+----------------+---------+----+---------+----------+---------+---------------+
| Collation | Charset | Id | Default | Compiled | Sortlen | Pad_attribute |
+----------------+---------+----+---------+----------+---------+---------------+
| gbk_bin | gbk | 87 | | Yes | 1 | PAD SPACE |
| gbk_chinese_ci | gbk | 28 | Yes | Yes | 1 | PAD SPACE |
+----------------+---------+----+---------+----------+---------+---------------+
2 rows in set (0.00 sec)
校对规则命名约定：相关的字符集名_语言名_ci(大小写不敏感)或_cs(大小写敏感)，或字符集名_bin(二元，即比较是基于字符编码的值，所以和语言无关，命名中无语言标识)。
如一下utf8对应的校对规则
mysql> show collation like 'utf8\_%';
+--------------------------+---------+-----+---------+----------+---------+---------------+
| Collation | Charset | Id | Default | Compiled | Sortlen | Pad_attribute |
+--------------------------+---------+-----+---------+----------+---------+---------------+
| utf8_bin | utf8 | 83 | | Yes | 1 | PAD SPACE |
| utf8_croatian_ci | utf8 | 213 | | Yes | 8 | PAD SPACE |
| utf8_czech_ci | utf8 | 202 | | Yes | 8 | PAD SPACE |
| utf8_danish_ci | utf8 | 203 | | Yes | 8 | PAD SPACE |
| utf8_esperanto_ci | utf8 | 209 | | Yes | 8 | PAD SPACE |
| utf8_estonian_ci | utf8 | 198 | | Yes | 8 | PAD SPACE |
| utf8_general_ci | utf8 | 33 | Yes | Yes | 1 | PAD SPACE |
| utf8_general_mysql500_ci | utf8 | 223 | | Yes | 1 | PAD SPACE |
| utf8_german2_ci | utf8 | 212 | | Yes | 8 | PAD SPACE |
| utf8_hungarian_ci | utf8 | 210 | | Yes | 8 | PAD SPACE |
| utf8_icelandic_ci | utf8 | 193 | | Yes | 8 | PAD SPACE |
| utf8_latvian_ci | utf8 | 194 | | Yes | 8 | PAD SPACE |
| utf8_lithuanian_ci | utf8 | 204 | | Yes | 8 | PAD SPACE |
| utf8_persian_ci | utf8 | 208 | | Yes | 8 | PAD SPACE |
| utf8_polish_ci | utf8 | 197 | | Yes | 8 | PAD SPACE |
| utf8_romanian_ci | utf8 | 195 | | Yes | 8 | PAD SPACE |
| utf8_roman_ci | utf8 | 207 | | Yes | 8 | PAD SPACE |
| utf8_sinhala_ci | utf8 | 211 | | Yes | 8 | PAD SPACE |
| utf8_slovak_ci | utf8 | 205 | | Yes | 8 | PAD SPACE |
| utf8_slovenian_ci | utf8 | 196 | | Yes | 8 | PAD SPACE |
| utf8_spanish2_ci | utf8 | 206 | | Yes | 8 | PAD SPACE |
| utf8_spanish_ci | utf8 | 199 | | Yes | 8 | PAD SPACE |
| utf8_swedish_ci | utf8 | 200 | | Yes | 8 | PAD SPACE |
| utf8_tolower_ci | utf8 | 76 | | Yes | 1 | PAD SPACE |
| utf8_turkish_ci | utf8 | 201 | | Yes | 8 | PAD SPACE |
| utf8_unicode_520_ci | utf8 | 214 | | Yes | 8 | PAD SPACE |
| utf8_unicode_ci | utf8 | 192 | | Yes | 8 | PAD SPACE |
| utf8_vietnamese_ci | utf8 | 215 | | Yes | 8 | PAD SPACE |
+--------------------------+---------+-----+---------+----------+---------+---------------+
28 rows in set (0.00 sec)
一，服务器级字符集和校对规则
在mysql服务启动时确定，默认使用latin1作为服务器级字符集。
可使用如下命令查看当前server的字符集和校对规则。
mysql> show variables like 'character_set_server';
+----------------------+-------+
| Variable_name | Value |
+----------------------+-------+
| character_set_server | utf8 |
+----------------------+-------+
1 row in set, 1 warning (0.00 sec)
mysql> show variables like 'collation_server';
+------------------+-----------------+
| Variable_name | Value |
+------------------+-----------------+
| collation_server | utf8_general_ci |
+------------------+-----------------+
1 row in set, 1 warning (0.00 sec)
二，数据库级字符集和校对规则
mysql数据库，默认的字符集为：armscii8，默认校对规则为：armscii8_general_ci。
mysql> show variables like
-> 'character_set_database';
+------------------------+----------+
| Variable_name | Value |
+------------------------+----------+
| character_set_database | armscii8 |
+------------------------+----------+
1 row in set, 1 warning (0.00 sec)
mysql> show variables like 'collation_database';
+--------------------+---------------------+
| Variable_name | Value |
+--------------------+---------------------+
| collation_database | armscii8_general_ci |
+--------------------+---------------------+
1 row in set, 1 warning (0.00 sec)
三，表级字符集和校对规则
可用如下命令查看表级字符集和校对规则。表级字符集和校对规则可在建表时显式指定。
mysql> show create table tcc \G;
*************************** 1. row ***************************
Table: tcc
Create Table: CREATE TABLE `tcc` (
`charset_desc` char(8) COLLATE utf8_bin DEFAULT NULL,
`collate_desc` char(8) COLLATE utf8_bin DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin
1 row in set (0.00 sec)
四，列字符集和校对规则
使用频率较少。