需要 >= MySQL
5.5.3版本、从库也必须是5.5的了、低版本不支持这个字符集、复制报错

查看数据库字符集

mysql> SHOW VARIABLES WHERE Variable_name LIKE 'character%' 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        |
| collation_connection   | utf8mb4_unicode_ci |
| collation_database    | utf8mb4_unicode_ci |
| collation_server     | utf8mb4_unicode_ci |
+--------------------------+--------------------+

重启 MySQL Server、检查字符集。

mysql> select * from SCHEMATA where SCHEMA_NAME='ttlsa';

+--------------+-------------+----------------------------+------------------------+----------+
| CATALOG_NAME | SCHEMA_NAME | DEFAULT_CHARACTER_SET_NAME | DEFAULT_COLLATION_NAME | SQL_PATH |
+--------------+-------------+----------------------------+------------------------+----------+
| def     | ttlsa   | utf8mb4          | utf8mb4_unicode_ci   | NULL   |
+--------------+-------------+----------------------------+------------------------+----------+

查看服务器字符集设置

mysql> select TABLE_SCHEMA,TABLE_NAME,TABLE_COLLATION from information_schema.TABLES;

+--------------------+----------------------------------------------------+--------------------+
| TABLE_SCHEMA    | TABLE_NAME                     | TABLE_COLLATION  |
+--------------------+----------------------------------------------------+--------------------+
[client]
 default-character-set = utf8mb4

[mysql]
 default-character-set = utf8mb4

[mysqld]
 character-set-client-handshake = FALSE
 character-set-server = utf8mb4
 collation-server = utf8mb4_unicode_ci
 init_connect='SET NAMES utf8mb4'
use information_schema;
SELECT concat("ALTER DATABASE `",table_schema,"` CHARACTER SET = utf8mb4 COLLATE = utf8mb4_unicode_ci;") as _sql 
FROM `TABLES` where table_schema like "DB_NAME" group by table_schema;
SELECT concat("ALTER TABLE `",table_schema,"`.`",table_name,"` CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;") as _sql 
FROM `TABLES` where table_schema like "DB_NAME" group by table_schema, table_name;
SELECT concat("ALTER TABLE `",table_schema,"`.`",table_name, "` CHANGE `",column_name,"` `",column_name,"` ",data_type,"(",character_maximum_length,") CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;") as _sql 
FROM `COLUMNS` where table_schema like "DB_NAME" and data_type in ('varchar');
SELECT concat("ALTER TABLE `",table_schema,"`.`",table_name, "` CHANGE `",column_name,"` `",column_name,"` ",data_type," CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;") as _sql 
FROM `COLUMNS` where table_schema like "DB_NAME" and data_type in ('text','tinytext','mediumtext','long

将Mysql的编码从utf8转换成utf8mb4。

utf8mb4和utf8到底有什么区别呢?原来以往的mysql的utf8一个字符最多3字节,而utf8mb4则扩展到一个字符最多能有4字节,所以能支持更多的字符集。

mysql> select TABLE_SCHEMA,TABLE_NAME,COLUMN_NAME,COLLATION_NAME from COLUMNS;

+--------------------+----------------------------------------------------+--------------------------------------------+--------------------+
| TABLE_SCHEMA    | TABLE_NAME                     | COLUMN_NAME                | COLLATION_NAME   |
+--------------------+----------------------------------------------------+--------------------------------------------+--------------------+

转换字符集语句

修改 my.cnf或者mysql.ini

查看列字符集

停止MySQL Server服务

查看表字符集

MySQL 需要支持 emoji
表情符号版本需要大于5.5.3,且字符集需要设置为utf8mb4 字符集。

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