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MySQL 8.4 参考手册 · 中文镜像

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MySQL 8.4 参考手册 / 12 种字符集、排序规则、Unicode / 12.2 MySQL 中的字符集和排序规则
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12.2 MySQL 中的字符集和排序规则12.2 Character Sets and Collations in MySQL

MySQL 服务器支持多种字符集,包括几种 Unicode 字符集。要显示可用的字符集,请使用INFORMATION_SCHEMA CHARACTER_SETS 表或 SHOW CHARACTER SET 语句。以下是部分列表。有关更完整的信息,请参见 第 12.10 节,“支持的字符集和排序规则”。MySQL Server supports multiple character sets, including several Unicode character sets. To display the available character sets, use the INFORMATION_SCHEMA CHARACTER_SETS table or the SHOW CHARACTER SET statement. A partial listing follows. For more complete information, see Section 12.10, “Supported Character Sets and Collations”.

mysql> SHOW CHARACTER SET;
+----------+---------------------------------+---------------------+--------+
| Charset  | Description                     | Default collation   | Maxlen |
+----------+---------------------------------+---------------------+--------+
| big5     | Big5 Traditional Chinese        | big5_chinese_ci     |      2 |
| binary   | Binary pseudo charset           | binary              |      1 |
...
| latin1   | cp1252 West European            | latin1_swedish_ci   |      1 |
...
| ucs2     | UCS-2 Unicode                   | ucs2_general_ci     |      2 |
...
| utf8mb3  | UTF-8 Unicode                   | utf8mb3_general_ci  |      3 |
| utf8mb4  | UTF-8 Unicode                   | utf8mb4_0900_ai_ci  |      4 |
...

默认情况下,SHOW CHARACTER SET 语句显示所有可用的字符集。它可以带一个可选的 LIKE 或 WHERE 子句,用于指示要匹配的字符集名称。下面的示例显示了一些 Unicode 字符集(基于 Unicode 转换格式的字符集):By default, the SHOW CHARACTER SET statement displays all available character sets. It takes an optional LIKE or WHERE clause that indicates which character set names to match. The following example shows some of the Unicode character sets (those based on Unicode Transformation Format):

mysql> SHOW CHARACTER SET LIKE 'utf%';
+---------+------------------+--------------------+--------+
| Charset | Description      | Default collation  | Maxlen |
+---------+------------------+--------------------+--------+
| utf16   | UTF-16 Unicode   | utf16_general_ci   |      4 |
| utf16le | UTF-16LE Unicode | utf16le_general_ci |      4 |
| utf32   | UTF-32 Unicode   | utf32_general_ci   |      4 |
| utf8mb3 | UTF-8 Unicode    | utf8mb3_general_ci |      3 |
| utf8mb4 | UTF-8 Unicode    | utf8mb4_0900_ai_ci |      4 |
+---------+------------------+--------------------+--------+

一个给定的字符集总是至少有一个排序规则,而且大多数字符集有多个。要列出字符集的显示排序规则,可以使用 INFORMATION_SCHEMA COLLATIONS 表或 SHOW COLLATION 语句。A given character set always has at least one collation, and most character sets have several. To list the display collations for a character set, use the INFORMATION_SCHEMA COLLATIONS table or the SHOW COLLATION statement.

默认情况下,SHOW COLLATION 语句显示所有可用的排序规则。它可以带有可选的 LIKE 或 WHERE 子句,用于指示显示哪些排序规则名称。例如,要查看默认字符集 utf8mb4 的排序规则,可以使用以下语句:By default, the SHOW COLLATION statement displays all available collations. It takes an optional LIKE or WHERE clause that indicates which collation names to display. For example, to see the collations for the default character set, utf8mb4, use this statement:

mysql> SHOW COLLATION WHERE Charset = 'utf8mb4';
+----------------------------+---------+-----+---------+----------+---------+---------------+
| Collation                  | Charset | Id  | Default | Compiled | Sortlen | Pad_attribute |
+----------------------------+---------+-----+---------+----------+---------+---------------+
| utf8mb4_0900_ai_ci         | utf8mb4 | 255 | Yes     | Yes      |       0 | NO PAD        |
| utf8mb4_0900_as_ci         | utf8mb4 | 305 |         | Yes      |       0 | NO PAD        |
| utf8mb4_0900_as_cs         | utf8mb4 | 278 |         | Yes      |       0 | NO PAD        |
| utf8mb4_0900_bin           | utf8mb4 | 309 |         | Yes      |       1 | NO PAD        |
| utf8mb4_bin                | utf8mb4 |  46 |         | Yes      |       1 | PAD SPACE     |
| utf8mb4_croatian_ci        | utf8mb4 | 245 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_cs_0900_ai_ci      | utf8mb4 | 266 |         | Yes      |       0 | NO PAD        |
| utf8mb4_cs_0900_as_cs      | utf8mb4 | 289 |         | Yes      |       0 | NO PAD        |
| utf8mb4_czech_ci           | utf8mb4 | 234 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_danish_ci          | utf8mb4 | 235 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_da_0900_ai_ci      | utf8mb4 | 267 |         | Yes      |       0 | NO PAD        |
| utf8mb4_da_0900_as_cs      | utf8mb4 | 290 |         | Yes      |       0 | NO PAD        |
| utf8mb4_de_pb_0900_ai_ci   | utf8mb4 | 256 |         | Yes      |       0 | NO PAD        |
| utf8mb4_de_pb_0900_as_cs   | utf8mb4 | 279 |         | Yes      |       0 | NO PAD        |
| utf8mb4_eo_0900_ai_ci      | utf8mb4 | 273 |         | Yes      |       0 | NO PAD        |
| utf8mb4_eo_0900_as_cs      | utf8mb4 | 296 |         | Yes      |       0 | NO PAD        |
| utf8mb4_esperanto_ci       | utf8mb4 | 241 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_estonian_ci        | utf8mb4 | 230 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_es_0900_ai_ci      | utf8mb4 | 263 |         | Yes      |       0 | NO PAD        |
| utf8mb4_es_0900_as_cs      | utf8mb4 | 286 |         | Yes      |       0 | NO PAD        |
| utf8mb4_es_trad_0900_ai_ci | utf8mb4 | 270 |         | Yes      |       0 | NO PAD        |
| utf8mb4_es_trad_0900_as_cs | utf8mb4 | 293 |         | Yes      |       0 | NO PAD        |
| utf8mb4_et_0900_ai_ci      | utf8mb4 | 262 |         | Yes      |       0 | NO PAD        |
| utf8mb4_et_0900_as_cs      | utf8mb4 | 285 |         | Yes      |       0 | NO PAD        |
| utf8mb4_general_ci         | utf8mb4 |  45 |         | Yes      |       1 | PAD SPACE     |
| utf8mb4_german2_ci         | utf8mb4 | 244 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_hr_0900_ai_ci      | utf8mb4 | 275 |         | Yes      |       0 | NO PAD        |
| utf8mb4_hr_0900_as_cs      | utf8mb4 | 298 |         | Yes      |       0 | NO PAD        |
| utf8mb4_hungarian_ci       | utf8mb4 | 242 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_hu_0900_ai_ci      | utf8mb4 | 274 |         | Yes      |       0 | NO PAD        |
| utf8mb4_hu_0900_as_cs      | utf8mb4 | 297 |         | Yes      |       0 | NO PAD        |
| utf8mb4_icelandic_ci       | utf8mb4 | 225 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_is_0900_ai_ci      | utf8mb4 | 257 |         | Yes      |       0 | NO PAD        |
| utf8mb4_is_0900_as_cs      | utf8mb4 | 280 |         | Yes      |       0 | NO PAD        |
| utf8mb4_ja_0900_as_cs      | utf8mb4 | 303 |         | Yes      |       0 | NO PAD        |
| utf8mb4_ja_0900_as_cs_ks   | utf8mb4 | 304 |         | Yes      |      24 | NO PAD        |
| utf8mb4_latvian_ci         | utf8mb4 | 226 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_la_0900_ai_ci      | utf8mb4 | 271 |         | Yes      |       0 | NO PAD        |
| utf8mb4_la_0900_as_cs      | utf8mb4 | 294 |         | Yes      |       0 | NO PAD        |
| utf8mb4_lithuanian_ci      | utf8mb4 | 236 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_lt_0900_ai_ci      | utf8mb4 | 268 |         | Yes      |       0 | NO PAD        |
| utf8mb4_lt_0900_as_cs      | utf8mb4 | 291 |         | Yes      |       0 | NO PAD        |
| utf8mb4_lv_0900_ai_ci      | utf8mb4 | 258 |         | Yes      |       0 | NO PAD        |
| utf8mb4_lv_0900_as_cs      | utf8mb4 | 281 |         | Yes      |       0 | NO PAD        |
| utf8mb4_persian_ci         | utf8mb4 | 240 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_pl_0900_ai_ci      | utf8mb4 | 261 |         | Yes      |       0 | NO PAD        |
| utf8mb4_pl_0900_as_cs      | utf8mb4 | 284 |         | Yes      |       0 | NO PAD        |
| utf8mb4_polish_ci          | utf8mb4 | 229 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_romanian_ci        | utf8mb4 | 227 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_roman_ci           | utf8mb4 | 239 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_ro_0900_ai_ci      | utf8mb4 | 259 |         | Yes      |       0 | NO PAD        |
| utf8mb4_ro_0900_as_cs      | utf8mb4 | 282 |         | Yes      |       0 | NO PAD        |
| utf8mb4_ru_0900_ai_ci      | utf8mb4 | 306 |         | Yes      |       0 | NO PAD        |
| utf8mb4_ru_0900_as_cs      | utf8mb4 | 307 |         | Yes      |       0 | NO PAD        |
| utf8mb4_sinhala_ci         | utf8mb4 | 243 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_sk_0900_ai_ci      | utf8mb4 | 269 |         | Yes      |       0 | NO PAD        |
| utf8mb4_sk_0900_as_cs      | utf8mb4 | 292 |         | Yes      |       0 | NO PAD        |
| utf8mb4_slovak_ci          | utf8mb4 | 237 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_slovenian_ci       | utf8mb4 | 228 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_sl_0900_ai_ci      | utf8mb4 | 260 |         | Yes      |       0 | NO PAD        |
| utf8mb4_sl_0900_as_cs      | utf8mb4 | 283 |         | Yes      |       0 | NO PAD        |
| utf8mb4_spanish2_ci        | utf8mb4 | 238 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_spanish_ci         | utf8mb4 | 231 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_sv_0900_ai_ci      | utf8mb4 | 264 |         | Yes      |       0 | NO PAD        |
| utf8mb4_sv_0900_as_cs      | utf8mb4 | 287 |         | Yes      |       0 | NO PAD        |
| utf8mb4_swedish_ci         | utf8mb4 | 232 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_tr_0900_ai_ci      | utf8mb4 | 265 |         | Yes      |       0 | NO PAD        |
| utf8mb4_tr_0900_as_cs      | utf8mb4 | 288 |         | Yes      |       0 | NO PAD        |
| utf8mb4_turkish_ci         | utf8mb4 | 233 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_unicode_520_ci     | utf8mb4 | 246 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_unicode_ci         | utf8mb4 | 224 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_vietnamese_ci      | utf8mb4 | 247 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_vi_0900_ai_ci      | utf8mb4 | 277 |         | Yes      |       0 | NO PAD        |
| utf8mb4_vi_0900_as_cs      | utf8mb4 | 300 |         | Yes      |       0 | NO PAD        |
| utf8mb4_zh_0900_as_cs      | utf8mb4 | 308 |         | Yes      |       0 | NO PAD        |
+----------------------------+---------+-----+---------+----------+---------+---------------+

有关这些排序规则的更多信息,请参阅 第 12.10.1 节,“Unicode 字符集”。For more information about those collations, see Section 12.10.1, “Unicode Character Sets”.

排序规则具有以下一般特征:Collations have these general characteristics:

  • 两个不同的字符集不能具有相同的排序规则。Two different character sets cannot have the same collation.

  • 每个字符集都有一个默认排序规则。例如,utf8mb4 和 latin1 的默认排序规则分别是 utf8mb4_0900_ai_ci 和 latin1_swedish_ci。INFORMATION_SCHEMA CHARACTER_SETS 表和 SHOW CHARACTER SET 语句显示每个字符集的默认排序规则。INFORMATION_SCHEMA COLLATIONS 表和 SHOW COLLATION 语句有一列,用于显示每个排序规则是否是其字符集的默认排序规则(如果是则显示 Yes,如果不是则为空)。Each character set has a default collation. For example, the default collations for utf8mb4 and latin1 are utf8mb4_0900_ai_ci and latin1_swedish_ci, respectively. The INFORMATION_SCHEMA CHARACTER_SETS table and the SHOW CHARACTER SET statement indicate the default collation for each character set. The INFORMATION_SCHEMA COLLATIONS table and the SHOW COLLATION statement have a column that indicates for each collation whether it is the default for its character set (Yes if so, empty if not).

  • 排序规则名称以与其关联的字符集名称开头,通常后面跟一个或多个表示其他排序规则特性的后缀。有关命名约定的更多信息,请参见 第 12.3.1 节,“排序规则命名约定”。Collation names start with the name of the character set with which they are associated, generally followed by one or more suffixes indicating other collation characteristics. For additional information about naming conventions, see Section 12.3.1, “Collation Naming Conventions”.

当一个字符集有多个排序规则时,可能不清楚哪种排序规则最适合特定的应用。为了避免选择不合适的排序规则,请使用代表性的数据值进行一些比较,以确保所选排序规则按预期对值进行排序。When a character set has multiple collations, it might not be clear which collation is most suitable for a given application. To avoid choosing an inappropriate collation, perform some comparisons with representative data values to make sure that a given collation sorts values the way you expect.