受@sdfor注释的启发，这里有一个bash脚本可以完成这项工作

#!/bin/bash

printf "### Converting MySQL character set ###\n\n"

printf "Enter the encoding you want to set: "
read -r CHARSET

# Get the MySQL username
printf "Enter mysql username: "
read -r USERNAME

# Get the MySQL password
printf "Enter mysql password for user %s:" "$USERNAME"
read -rs PASSWORD

DBLIST=( mydatabase1 mydatabase2 )

printf "\n"


for DB in "${DBLIST[@]}"
do
(
    echo 'ALTER DATABASE `'"$DB"'` CHARACTER SET utf8 COLLATE `'"$CHARSET"'`;'
    mysql "$DB" -u"$USERNAME" -p"$PASSWORD" -e "SHOW TABLES" --batch --skip-column-names \
    | xargs -I{} echo 'ALTER TABLE `'{}'` CONVERT TO CHARACTER SET utf8 COLLATE `'"$CHARSET"'`;'
) \
| mysql "$DB" -u"$USERNAME" -p"$PASSWORD"

echo "$DB database done..."
done

echo "### DONE ###"
exit

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"

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…

在继续之前，请确保您:已完成完全数据库备份!

步骤1:数据库级别更改

标识数据库的排序规则和字符集 选择default_character_set_name, default_collation_name from information_schema。图式年代 WHERE schema_name = 'your_database_name' 和 (DEFAULT_CHARACTER_SET_NAME != 'utf8' 或 DEFAULT_COLLATION_NAME不像'utf8%'); 修复数据库的排序规则 ALTER DATABASE DATABASE utf8 COLLATE utf8_unicode_ci;

步骤2:表级别更改

Identifying Database Tables with the incorrect character set or collation SELECT CONCAT( 'ALTER TABLE ', table_name, ' CHARACTER SET utf8 COLLATE utf8_general_ci; ', 'ALTER TABLE ', table_name, ' CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci; ') FROM information_schema.TABLES AS T, information_schema.`COLLATION_CHARACTER_SET_APPLICABILITY` AS C WHERE C.collation_name = T.table_collation AND T.table_schema = 'your_database_name' AND (C.CHARACTER_SET_NAME != 'utf8' OR C.COLLATION_NAME not like 'utf8%') Adjusting table columns' collation and character set

捕获上层sql输出并运行它。(如后)

ALTER TABLE rma CHARACTER SET utf8 COLLATE utf8_general_ci;ALTER TABLE rma CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci;  
ALTER TABLE rma_history CHARACTER SET utf8 COLLATE utf8_general_ci;ALTER TABLE rma_history CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci;  
ALTER TABLE rma_products CHARACTER SET utf8 COLLATE utf8_general_ci;ALTER TABLE rma_products CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci;  
ALTER TABLE rma_report_period CHARACTER SET utf8 COLLATE utf8_general_ci;ALTER TABLE rma_report_period CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci;  
ALTER TABLE rma_reservation CHARACTER SET utf8 COLLATE utf8_general_ci;ALTER TABLE rma_reservation CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci;  
ALTER TABLE rma_supplier_return CHARACTER SET utf8 COLLATE utf8_general_ci;ALTER TABLE rma_supplier_return CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci;  
ALTER TABLE rma_supplier_return_history CHARACTER SET utf8 COLLATE utf8_general_ci;ALTER TABLE rma_supplier_return_history CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci;  
ALTER TABLE rma_supplier_return_product CHARACTER SET utf8 COLLATE utf8_general_ci;ALTER TABLE rma_supplier_return_product CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci; 

参考网址:https://confluence.atlassian.com/display/CONFKB/How+to+Fix+the+Collation+and+Character+Set+of+a+MySQL+Database

Make a backup! Then you need to set the default char sets on the database. This does not convert existing tables, it only sets the default for newly created tables. ALTER DATABASE dbname CHARACTER SET utf8 COLLATE utf8_general_ci; Then, you will need to convert the char set on all existing tables and their columns. This assumes that your current data is actually in the current char set. If your columns are set to one char set but your data is really stored in another then you will need to check the MySQL manual on how to handle this. ALTER TABLE tbl_name CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci;

对于有大量表的数据库，你可以使用一个简单的php脚本来更新数据库和所有表的字符集，使用以下方法:

$conn = mysqli_connect($host, $username, $password, $database);

if ($conn->connect_error) {
  die("Connection failed: " . $conn->connect_error);
}

$alter_database_charset_sql = "ALTER DATABASE ".$database." CHARACTER SET utf8 COLLATE utf8_unicode_ci";
mysqli_query($conn, $alter_database_charset_sql);

$show_tables_result = mysqli_query($conn, "SHOW TABLES");
$tables  = mysqli_fetch_all($show_tables_result);

foreach ($tables as $index => $table) {
  $alter_table_sql = "ALTER TABLE ".$table[0]." CONVERT TO CHARACTER SET utf8  COLLATE utf8_unicode_ci";
  $alter_table_result = mysqli_query($conn, $alter_table_sql);
  echo "<pre>";
  var_dump($alter_table_result);
  echo "</pre>";
}