【MySQL】MySQL 8.0支持utf8mb4

utf8mb4 utf8mb3 utf8

Refer to

• The utf8mb4 Character Set
• The utf8 Character Set (Alias for utf8mb3)

  MySQL在5.5.3之后增加了utf8mb4字符编码，mb4即most bytes 4。简单说utf8mb4是utf8的超集并完全兼容utf8，能够用四个字节存储更多的字符。而utf8是utf8mb3的别名。标准的UTF-8字符集编码是可以用1~4个字节去编码21位字符，但是MySQL其实实现的utf8只是使用3个字节而已，utf8mb4才是真正意义上的utf8。

  如果数据库表字段设置的字符集不是utf8mb4，却插入类似emjoy表情的时候：

• 严格模式下会出现Incorrect string value: /xF0/xA1/x8B/xBE/xE5/xA2… for column 'name'这样的错误
• 非严格模式下此后的数据会被截断

---

排序字符集

Refer to: Collation Naming Conventions

Suffix	Meaning	Remark
_ai	Accent insensitive
_as	Accent sensitive
_ci	Case insensitive	不分区大小写
_cs	case-sensitive	区分大小写
_bin	Binary	二进制存储，区分大小写

utf8mb4_ unicode_ ci VS utf8mb4_ general_ ci

Refer to: What's the difference between utf8_general_ci and utf8_unicode_ci

• utf8_general_ci校对速度快，但准确度稍差。
• utf8_unicode_ci准确度高，但校对速度稍慢。

数据库一般默认选择utf8mb4_general_ci;
如果应用有德语、法语或者俄语，请一定使用utf8mb4_unicode_ci

配置

vim /etc/my.cnf

[client] 
default-character-set = utf8mb4 

[mysql] 
default-character-set = utf8mb4 

[mysqld] 
# character-set-client-handshake = FALSE 
character-set-server = utf8mb4 
collation-server = utf8mb4_general_ci 
init_connect='SET NAMES utf8mb4'

检查目前MySQL的字符集

mysql> SHOW VARIABLES WHERE Variable_name LIKE 'character\_set\_%' OR Variable_name LIKE 'collation%';
+--------------------------+-----------------+
| Variable_name            | Value           |
+--------------------------+-----------------+
| character_set_client     | utf8            |
| character_set_connection | utf8            |
| character_set_database   | utf8            |
| character_set_filesystem | binary          |
| character_set_results    | utf8            |
| character_set_server     | utf8            |
| character_set_system     | utf8            |
| collation_connection     | utf8_general_ci |
| collation_database       | utf8_general_ci |
| collation_server         | utf8_general_ci |
+--------------------------+-----------------+
10 rows in set (0.00 sec)

总结

• MySQL版本5.5.3+
• MySQL Connector/J Java驱动5.1.13+
• /etc/my.cnf配置中添加配置，详见上面
• 排序字符集选用utf8mb4_unicode_ci
• 列（字段）> 表 > 数据库

备注：
  其实只要数据库支持utfbmb4(show char set)，及时MySQL配置(/etc/my.cnf)中配置的默认字符集是utf8，也可以直接指定数据库、表、字段的字符集为utf8mb4，然后在连接的时候指定字符集为utf8mb4即可。
比如设置Java的连接参数中characterEncoding=utf8mb4

查看MySQL支持的字符集列表：

root@localhost:3306.sock [test]> show char set;
+----------+---------------------------------+---------------------+--------+
| Charset  | Description                     | Default collation   | Maxlen |
+----------+---------------------------------+---------------------+--------+
| big5     | Big5 Traditional Chinese        | big5_chinese_ci     |      2 |
| dec8     | DEC West European               | dec8_swedish_ci     |      1 |
| cp850    | DOS West European               | cp850_general_ci    |      1 |
| hp8      | HP West European                | hp8_english_ci      |      1 |
| koi8r    | KOI8-R Relcom Russian           | koi8r_general_ci    |      1 |
| latin1   | cp1252 West European            | latin1_swedish_ci   |      1 |
| latin2   | ISO 8859-2 Central European     | latin2_general_ci   |      1 |
| swe7     | 7bit Swedish                    | swe7_swedish_ci     |      1 |
| ascii    | US ASCII                        | ascii_general_ci    |      1 |
| ujis     | EUC-JP Japanese                 | ujis_japanese_ci    |      3 |
| sjis     | Shift-JIS Japanese              | sjis_japanese_ci    |      2 |
| hebrew   | ISO 8859-8 Hebrew               | hebrew_general_ci   |      1 |
| tis620   | TIS620 Thai                     | tis620_thai_ci      |      1 |
| euckr    | EUC-KR Korean                   | euckr_korean_ci     |      2 |
| koi8u    | KOI8-U Ukrainian                | koi8u_general_ci    |      1 |
| gb2312   | GB2312 Simplified Chinese       | gb2312_chinese_ci   |      2 |
| greek    | ISO 8859-7 Greek                | greek_general_ci    |      1 |
| cp1250   | Windows Central European        | cp1250_general_ci   |      1 |
| gbk      | GBK Simplified Chinese          | gbk_chinese_ci      |      2 |
| latin5   | ISO 8859-9 Turkish              | latin5_turkish_ci   |      1 |
| armscii8 | ARMSCII-8 Armenian              | armscii8_general_ci |      1 |
| utf8     | UTF-8 Unicode                   | utf8_general_ci     |      3 |
| ucs2     | UCS-2 Unicode                   | ucs2_general_ci     |      2 |
| cp866    | DOS Russian                     | cp866_general_ci    |      1 |
| keybcs2  | DOS Kamenicky Czech-Slovak      | keybcs2_general_ci  |      1 |
| macce    | Mac Central European            | macce_general_ci    |      1 |
| macroman | Mac West European               | macroman_general_ci |      1 |
| cp852    | DOS Central European            | cp852_general_ci    |      1 |
| latin7   | ISO 8859-13 Baltic              | latin7_general_ci   |      1 |
| utf8mb4  | UTF-8 Unicode                   | utf8mb4_general_ci  |      4 |
| cp1251   | Windows Cyrillic                | cp1251_general_ci   |      1 |
| utf16    | UTF-16 Unicode                  | utf16_general_ci    |      4 |
| utf16le  | UTF-16LE Unicode                | utf16le_general_ci  |      4 |
| cp1256   | Windows Arabic                  | cp1256_general_ci   |      1 |
| cp1257   | Windows Baltic                  | cp1257_general_ci   |      1 |
| utf32    | UTF-32 Unicode                  | utf32_general_ci    |      4 |
| binary   | Binary pseudo charset           | binary              |      1 |
| geostd8  | GEOSTD8 Georgian                | geostd8_general_ci  |      1 |
| cp932    | SJIS for Windows Japanese       | cp932_japanese_ci   |      2 |
| eucjpms  | UJIS for Windows Japanese       | eucjpms_japanese_ci |      3 |
| gb18030  | China National Standard GB18030 | gb18030_chinese_ci  |      4 |
+----------+---------------------------------+---------------------+--------+
41 rows in set (0.00 sec)

 

建议

数据库在设置字符集的时候，设置成utf8mb4格式！