对我来说唯一有效的解决方案是:http://docs.moodle.org/23/en/Converting_your_MySQL_database_to_UTF8

转换包含表的数据库

mysqldump -uusername -ppassword -c -e --default-character-set=utf8 --single-transaction --skip-set-charset --add-drop-database -B dbname > dump.sql

cp dump.sql dump-fixed.sql
vim dump-fixed.sql

:%s/DEFAULT CHARACTER SET latin1/DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci/
:%s/DEFAULT CHARSET=latin1/DEFAULT CHARSET=utf8/
:wq

mysql -uusername -ppassword < dump-fixed.sql

对我来说唯一有效的解决方案是:http://docs.moodle.org/23/en/Converting_your_MySQL_database_to_UTF8

转换包含表的数据库

mysqldump -uusername -ppassword -c -e --default-character-set=utf8 --single-transaction --skip-set-charset --add-drop-database -B dbname > dump.sql

cp dump.sql dump-fixed.sql
vim dump-fixed.sql

:%s/DEFAULT CHARACTER SET latin1/DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci/
:%s/DEFAULT CHARSET=latin1/DEFAULT CHARSET=utf8/
:wq

mysql -uusername -ppassword < dump-fixed.sql

mysqldump -uusername -ppassword -c -e --default-character-set=utf8 --single-transaction --skip-set-charset --add-drop-database -B dbname > dump.sql
cp dump.sql dump-fixed.sql
vim dump-fixed.sql


:%s/DEFAULT CHARACTER SET latin1/DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci/
:%s/DEFAULT CHARSET=latin1/DEFAULT CHARSET=utf8/
:wq

mysql -uusername -ppassword < dump-fixed.sql

你可以创建sql来更新所有的表:

SELECT CONCAT("ALTER TABLE ",TABLE_SCHEMA,".",TABLE_NAME," CHARACTER SET utf8 COLLATE utf8_general_ci;   ",
    "ALTER TABLE ",TABLE_SCHEMA,".",TABLE_NAME," CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci;  ") 
    AS alter_sql
FROM information_schema.TABLES
WHERE TABLE_SCHEMA = "your_database_name";

捕获输出并运行它。

阿诺德•丹尼尔斯(Arnold Daniels)的回答更为优雅。

utf8到utf8mb4:

1.显示所有数据库默认字符集:

SELECT SCHEMA_NAME 'YOUR_DATABASE_NAME', 
default_character_set_name 'charset', 
DEFAULT_COLLATION_NAME 'collation' 
FROM information_schema.SCHEMATA;

2.显示所有表的状态(字符集)，关注列的“collation”:

use YOUR_DATABASE_NAME;    
SHOW TABLE STATUS ;

3.生成转换sql: 转换数据库和所有表utf8mb4,utf8mb4_unicode_ci

USE information_schema;
SELECT CONCAT("ALTER DATABASE `",table_schema,"` CHARACTER SET = utf8mb4 COLLATE = utf8mb4_unicode_ci;") AS _sql
FROM `TABLES` WHERE table_schema LIKE "YOUR_DATABASE_NAME" AND TABLE_TYPE='BASE TABLE' GROUP BY table_schema UNION
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 "YOUR_DATABASE_NAME" AND TABLE_TYPE='BASE TABLE' GROUP BY table_schema, TABLE_NAME 
/*include all columns, commonly don't need this.*/
/*
UNION
SELECT CONCAT("ALTER TABLE `",`COLUMNS`.table_schema,"`.`",`COLUMNS`.table_name, "` CHANGE `",column_name,"` `",column_name,"` ",data_type,"(",character_maximum_length,") CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci",IF(is_nullable="YES"," NULL"," NOT NULL"),";") AS _sql 
FROM `COLUMNS` INNER JOIN `TABLES` ON `TABLES`.table_name = `COLUMNS`.table_name WHERE `COLUMNS`.table_schema like "YOUR_DATABASE_NAME" and data_type in ('varchar','char') AND TABLE_TYPE='BASE TABLE' UNION
SELECT CONCAT("ALTER TABLE `",`COLUMNS`.table_schema,"`.`",`COLUMNS`.table_name, "` CHANGE `",column_name,"` `",column_name,"` ",data_type," CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci",IF(is_nullable="YES"," NULL"," NOT NULL"),";") AS _sql 
FROM `COLUMNS` INNER JOIN `TABLES` ON `TABLES`.table_name = `COLUMNS`.table_name WHERE `COLUMNS`.table_schema like "YOUR_DATABASE_NAME" and data_type in ('text','tinytext','mediumtext','longtext') AND TABLE_TYPE='BASE TABLE';
*/

4.运行生成的SQL语句。

5.刷新数据库。

6.检查:

SHOW TABLE STATUS ;

要更改数据库本身的字符集编码为UTF-8，在mysql>提示符处键入以下命令。将DBNAME替换为数据库名称。

ALTER DATABASE DBNAME CHARACTER SET utf8 COLLATE utf8_general_ci;