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自从上次重装系统之后，装好 MySQL 5.7 之后就没管过，今天发现居然存储不了中文，使用 show variables like 'char%'; 查询发现居然不是 utf8 而是 Latin 编码，怪不得不支持中文。

mysql> SHOW VARIABLES WHERE Variable_name LIKE 'character_set_%' OR Variable_name 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       | C:\Program Files\MySQL\MySQL Server 5.7\share\charsets\ |
| collation_connection     | utf8mb4_general_ci                                      |
| collation_database       | latin1_swedish_ci                                       |
| collation_server         | latin1_swedish_ci                                       |
+--------------------------+---------------------------------------------------------+
11 rows in set, 1 warning (0.00 sec)

怒修改，编辑 my.ini 文件，文件位置 C:\ProgramData\MySQL\MySQL Server 5.7\my.ini 当然可以在 Windows 服务中找到，添加部分如下

[client]
default-character-set = utf8mb4
port=3306

[mysql]
no-beep
default-character-set = utf8mb4

[mysqld]
init-connect = 'SET NAMES utf8mb4'
character-set-server = utf8mb4
collation-server=utf8mb4_unicode_ci
port=3306

然后重启 MySQL5.7 服务
修改后如下

mysql> SHOW VARIABLES WHERE Variable_name LIKE 'character_set_%' OR Variable_name 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       | C:\Program Files\MySQL\MySQL Server 5.7\share\charsets\ |
| collation_connection     | utf8mb4_general_ci                                      |
| collation_database       | utf8mb4_unicode_ci                                      |
| collation_server         | utf8mb4_unicode_ci                                      |
+--------------------------+---------------------------------------------------------+
11 rows in set, 1 warning (0.00 sec)

这样修改之后，虽然新建数据库新建表都是 utf8了，但是原来数据库和数据表还要手工修改。

修改已经存在的数据库编码 ALTER DATABASE db_name CHARACTER SET = utf8mb4 COLLATE = utf8mb4_unicode_ci; 其中 da_name 为需要修改的数据库名。

修改数据表编码用了 segmentfault 上的大神批量生成修改数据表修改语句方案。

SELECT 
CONCAT("ALTER TABLE `", TABLE_NAME,"` CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;") 
AS target_tables
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_SCHEMA="db_name"
AND TABLE_TYPE="BASE TABLE"

其中 da_name 为需要修改的数据库名，这样就会把该数据库中数据表修改语句生成出来，再运行即可。

参考链接：
1. MySQL 批量修改数据表编码及字符集
2. 修改MySQL的字符集为utf8mb4
3. MYSQL中的COLLATE是什么？