The website would use Japanese and therefore the database charset should have been set "utf8mb4" as. I, however, did
CREATE DATABASE without specific options and so it was "c" instead of "utf8mb4" unfortunately.
I updated its charset and collation with this SQL:
-- accessing through `mysql -u <user> -p` ALTER DATABASE <database> \ CHARACTER SET='utf8mb4' \ COLLATE='utf8mb4_unicode_ci' \ ;
Well, it is also able to get charsets via SQL:
SELECT SCHEMA_NAME, DEFAULT_CHARACTER_SET_NAME, DEFAULT_COLLATION_NAME \ FROM information_schema.SCHEMATA;