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

使用ALTER DATABASE和ALTER TABLE命令。

ALTER DATABASE databasename CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
ALTER TABLE tablename CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;

或者如果你仍然使用MySQL 5.5.2或更早的版本，不支持4字节UTF-8，使用utf8而不是utf8mb4:

ALTER DATABASE databasename CHARACTER SET utf8 COLLATE utf8_unicode_ci;
ALTER TABLE tablename CONVERT TO CHARACTER SET utf8 COLLATE utf8_unicode_ci;

命令行解决方案和排除视图

我只是在为像我和布莱恩这样在我们的数据库中有视图的人完成@Jasny的回答。

如果你有这样的错误:

ERROR 1347 (HY000) at line 17: 'dbname.table_name' is not of type 'BASE TABLE'

这是因为你可能有自己的观点，你需要排除它们。 但是当试图排除它们时，MySQL返回2列而不是1列。

SHOW FULL TABLES WHERE Table_Type = 'BASE TABLE';
-- table_name1  BASE TABLE
-- table_name2  BASE TABLE

因此，我们必须用awk修改Jasny的命令，只提取包含表名的第一列。

DB="dbname"
(
    echo 'ALTER DATABASE `'"$DB"'` CHARACTER SET utf8 COLLATE utf8_general_ci;'
    mysql "$DB" -e "SHOW FULL TABLES WHERE Table_Type = 'BASE TABLE'" --batch --skip-column-names \
    | awk '{print $1 }' \
    | xargs -I{} echo 'ALTER TABLE `'{}'` CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci;'
) \
| mysql "$DB"

简单复制/粘贴的一行程序

DB="dbname"; ( echo 'ALTER DATABASE `'"$DB"'` CHARACTER SET utf8 COLLATE utf8_general_ci;'; mysql "$DB" -e "SHOW FULL TABLES WHERE Table_Type = 'BASE TABLE'" --batch --skip-column-names | awk '{print $1 }' | xargs -I{} echo 'ALTER TABLE `'{}'` CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci;' ) | mysql "$DB"

使用HeidiSQL。它是免费的，而且是一个非常好的数据库工具。

从工具菜单，进入批量表编辑器

选择完整的数据库或选择表进行转换，

tick更改默认排序规则:utf8mb4_general_ci tick转换为字符集:utf8

执行

这将在短短几秒钟内将完整的数据库从拉丁语转换为utf8。

工作就像一个魅力:)

HeidiSQL默认连接为utf8，因此任何特殊字符现在都应该被视为字符(æ ø å)，而不是在检查表数据时被编码。

从latin到utf8的真正陷阱是确保pdo与utf8字符集连接。如果不是，你会得到垃圾数据插入到utf8表和问号在你的网页上到处都是，让你认为表数据不是utf8…

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 ;

在命令行shell上

如果你是一个命令行shell，你可以非常快地做到这一点。只需填写“dbname”:D

DB="dbname"
(
    echo 'ALTER DATABASE `'"$DB"'` CHARACTER SET utf8 COLLATE utf8_general_ci;'
    mysql "$DB" -e "SHOW TABLES" --batch --skip-column-names \
    | xargs -I{} echo 'ALTER TABLE `'{}'` CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci;'
) \
| mysql "$DB"

简单复制/粘贴的一行程序

DB="dbname"; ( echo 'ALTER DATABASE `'"$DB"'` CHARACTER SET utf8 COLLATE utf8_general_ci;'; mysql "$DB" -e "SHOW TABLES" --batch --skip-column-names | xargs -I{} echo 'ALTER TABLE `'{}'` CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci;' ) | mysql "$DB"