设置MySQL/MariaDB 数据库默认编码为utf8mb4 （推荐）

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本文介绍了如何将MySQL/MariaDB的默认字符集从GBK或latin1切换到utf8mb4，强调了通过命令行更改设置在重启后会失效的问题，并提供了将配置写入文件以确保永久生效的方法。

MySQL/MariaDB中的UTF-8并不是真正的UTF-8，其中的UTF8MB4才是真正的UTF-8。因此推荐使用UTF8MB4。

先查看自己数据库的默认字符集：

MariaDB [(none)]> show variables like "%character%";show variables like "%collation%";
+--------------------------+----------------------------------------------------+
| Variable_name            | Value                                              |
+--------------------------+----------------------------------------------------+
| character_set_client     | gbk                                                |
| character_set_connection | gbk                                                |
| character_set_database   | latin1                                             |
| character_set_filesystem | binary                                             |
| character_set_results    | gbk                                                |
| character_set_server     | latin1                                             |
| character_set_system     | utf8                                               |
| character_sets_dir       | D:\download\mariadb-10.3.15-winx64\share\charsets\ |
+--------------------------+----------------------------------------------------+
8 rows in set (0.001 sec)

+----------------------+-------------------+
| Variable_name        | Value             |
+----------------------+-------------------+
| collation_connection | gbk_chinese_ci    |
| collation_database   | latin1_swedish_ci |
| collation_server     | latin1_swedish_ci |
+----------------------+-------------------+
3 rows in set (0.001 sec)

看到了默认的基本都是GBK和latin1。

然后查看有哪些CHARSET可以使用：

MariaDB [(none)]> SHOW CHARSET;
+----------+-----------------------------+---------------------+--------+
| 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 |
+----------+-----------------------------+---------------------+--------+
40 rows in set (0.000 sec)

看到了里面有utf8mb4 ，非常老的MySQL可能不存在utf8mb4 编码。
运行命令：

MariaDB [(none)]>  SET NAMES 'utf8mb4';
Query OK, 0 rows affected (0.000 sec)

MariaDB [(none)]> show variables like "%character%";show variables like "%collation%";
+--------------------------+----------------------------------------------------+
| Variable_name            | Value                                              |
+--------------------------+----------------------------------------------------+
| character_set_client     | utf8mb4                                            |
| character_set_connection | utf8mb4                                            |
| character_set_database   | latin1                                             |
| character_set_filesystem | binary                                             |
| character_set_results    | utf8mb4                                            |
| character_set_server     | latin1                                             |
| character_set_system     | utf8                                               |
| character_sets_dir       | D:\download\mariadb-10.3.15-winx64\share\charsets\ |
+--------------------------+----------------------------------------------------+
8 rows in set (0.001 sec)

+----------------------+--------------------+
| Variable_name        | Value              |
+----------------------+--------------------+
| collation_connection | utf8mb4_general_ci |
| collation_database   | latin1_swedish_ci  |
| collation_server     | latin1_swedish_ci  |
+----------------------+--------------------+
3 rows in set (0.001 sec)

可以看到collation_connection，character_set_client,character_set_connection,character_set_results都变成了utf8mb4了。
再运行命令：

MariaDB [(none)]> set character_set_server = utf8mb4;set character_set_database = utf8mb4;set collation_database = utf8mb4_general_ci ;set collation_server = utf8mb4_general_ci ;
Query OK, 0 rows affected (0.000 sec)

Query OK, 0 rows affected (0.000 sec)

Query OK, 0 rows affected (0.000 sec)

Query OK, 0 rows affected (0.000 sec)

MariaDB [(none)]> show variables like "%character%";show variables like "%collation%";
+--------------------------+----------------------------------------------------+
| Variable_name            | Value                                              |
+--------------------------+----------------------------------------------------+
| character_set_client     | utf8mb4                                            |
| character_set_connection | utf8mb4                                            |
| character_set_database   | utf8mb4                                            |
| character_set_filesystem | binary                                             |
| character_set_results    | utf8mb4                                            |
| character_set_server     | utf8mb4                                            |
| character_set_system     | utf8                                               |
| character_sets_dir       | D:\download\mariadb-10.3.15-winx64\share\charsets\ |
+--------------------------+----------------------------------------------------+
8 rows in set (0.001 sec)

+----------------------+--------------------+
| Variable_name        | Value              |
+----------------------+--------------------+
| collation_connection | utf8mb4_general_ci |
| collation_database   | utf8mb4_general_ci |
| collation_server     | utf8mb4_general_ci |
+----------------------+--------------------+
3 rows in set (0.001 sec)

看到已经都变成了utf8mb4。

最坑的一点来了，如果MySQL/MariaDB重启了，上面的设置就无效了！！！
最坑的一点来了，如果MySQL/MariaDB重启了，上面的设置就无效了！！！
最坑的一点来了，如果MySQL/MariaDB重启了，上面的设置就无效了！！！
所以你需要把配置写到文件中去。运行命令查看你应该写到哪个文件：

PS C:\Users\peter> mysqld --help --verbose
2019-06-24 10:01:13 0 [Note] Plugin 'FEEDBACK' is disabled.
D:\download\mariadb-10.3.15-winx64\bin\mysqld.exe  Ver 10.3.15-MariaDB for Win64 on AMD64 (mariadb.org binary distribution)
Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

Starts the MariaDB database server.

Usage: D:\download\mariadb-10.3.15-winx64\bin\mysqld.exe [OPTIONS]
NT and Win32 specific options:
  --install                     Install the default service (NT).
  --install-manual              Install the default service started manually (NT).
  --install service_name        Install an optional service (NT).
  --install-manual service_name Install an optional service started manually (NT).
  --remove                      Remove the default service from the service list (NT).
  --remove service_name         Remove the service_name from the service list (NT).
  --enable-named-pipe           Only to be used for the default server (NT).
  --standalone                  Dummy option to start as a standalone server (NT).


Default options are read from the following files in the given order:
C:\Windows\my.ini C:\Windows\my.cnf C:\my.ini C:\my.cnf D:\download\mariadb-10.3.15-winx64\my.ini D:\download\mariadb-10.3.15-winx64\my.cnf D:\download\mariadb-10.3.15-winx64\data\my.ini D:\download\mariadb-10.3.15-winx64\data\my.cnf
The following groups are read: mysqld server mysqld-10.3 mariadb mariadb-10.3 client-server

里面提到了文件应该放在目录里D:\download\mariadb-10.3.15-winx64\data\my.cnf
新建文件my.cnf，内容如下：

[client]
default-character-set=utf8mb4

[mysql]
default-character-set=utf8mb4


[mysqld]
collation-server = utf8mb4_unicode_ci
init-connect='SET NAMES utf8mb4'
character-set-server = utf8mb4

然后重启数据库，发现字符集已经变成了utf8mb4：

MariaDB [(none)]> show variables like "%character%";show variables like "%collation%";
+--------------------------+----------------------------------------------------+
| Variable_name            | Value                                              |
+--------------------------+----------------------------------------------------+
| character_set_client     | utf8mb4                                            |
| character_set_connection | utf8mb4                                            |
| character_set_database   | utf8mb4                                            |
| character_set_filesystem | binary                                             |
| character_set_results    | utf8mb4                                            |
| character_set_server     | utf8mb4                                            |
| character_set_system     | utf8                                               |
| character_sets_dir       | D:\download\mariadb-10.3.15-winx64\share\charsets\ |
+--------------------------+----------------------------------------------------+
8 rows in set (0.001 sec)

+----------------------+--------------------+
| Variable_name        | Value              |
+----------------------+--------------------+
| collation_connection | utf8mb4_general_ci |
| collation_database   | utf8mb4_unicode_ci |
| collation_server     | utf8mb4_unicode_ci |
+----------------------+--------------------+
3 rows in set (0.001 sec)

修改成功。

如果你的数据库中已经存在表了，建议进行修复一下

mysqlcheck -u root -p --auto-repair --optimize --all-databases