How to modify mariadb chartset at once? - mysql

Question

I am developing with mariadb and Spring, JdbcTemplate.
At first, we made DB charset as utf8, but now we have to change it into utf8mb4 because of emojis.
Till now I update individual charset with query something like below.
ALTER TABLE WT_WORKS CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
ALTER TABLE WT_WORKS CHANGE WORKS_TITLE WORKS_TITLE VARCHAR(300) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
ALTER TABLE WT_WORKS CHANGE WORKS_DESC WORKS_DESC VARCHAR(500) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
However It is now efficient because of table relations. For example when I insert into WT_WORKS, also need to into WT_WRITERS. It looks impossible to find every tables and columns.
So I want to know change these at once.(Including Procedures and Functions). -- something like (v_name VARCHAR(10)) into (v_name VARCHAR(10) CHARSET utf8mb4).
Thanks for answer.
FYI. my my.cnf got follow settings
[client]
default-character-set=utf8mb4
[mysqld]
collation-server = utf8mb4_unicode_ci
character-set-server = utf8mb4
[client]
default-character-set = utf8mb4

Answer 1

SELECT DISTINCT TABLE_SCHEMA, TABLE_NAME
FROM information_schema.COLUMNS
WHERE CHARACTER_SET_NAME = 'utf8'
will list all the tables that still have some column set to utf8. When them, do ALTER TABLE .. CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_520_ci;
This should generate all the ALTERs you need:
SELECT DISTINCT
CONCAT(
"ALTER TABLE ", TABLE_SCHEMA, ".", TABLE_NAME,
" CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_520_ci;"
)
FROM information_schema.COLUMNS
WHERE CHARACTER_SET_NAME = 'utf8'
Then copy and paste them into the mysql command line tool.
Caveat: If you have some columns with charsets other than utf8, they will be blindly converted to utf8mb4. This would be bad for hex, ascii, etc., columns, such as country_code, uuid, md5, etc.
You could do something similar to change individual columns instead.
You do not need to do both.