解决方法

1、进入数据库，直接运行下列语句：

alter table typecho_comments convert to character set utf8mb4 collate utf8mb4_general_ci;
alter table typecho_contents convert to character set utf8mb4 collate utf8mb4_general_ci;
alter table typecho_fields convert to character set utf8mb4 collate utf8mb4_general_ci;
alter table typecho_metas convert to character set utf8mb4 collate utf8mb4_general_ci;
alter table typecho_options convert to character set utf8mb4 collate utf8mb4_general_ci;
alter table typecho_relationships convert to character set utf8mb4 collate utf8mb4_general_ci;
alter table typecho_users convert to character set utf8mb4 collate utf8mb4_general_ci;

2、修改数据库的配置文件

网站根目录数据库配置文件config.inc.php，大约在60行

/** 定义数据库参数 */
$db = new Typecho_Db('Pdo_Mysql', 'typecho_');
$db->addServer(array (
...
'charset' => 'utf8mb4', // 将原来的utf8修改为 utf8mb4
...
), Typecho_Db::READ | Typecho_Db::WRITE);
Typecho_Db::set($db);