How to make MySQL handle UTF-8 properly

Question

One of the responses to a question I asked yesterday suggested that I should make sure my database can handle UTF-8 characters correctly. How I can do this with MySQL?

Answer 1

Update:

Short answer - You should almost always be using the utf8mb4 charset and utf8mb4_unicode_ci collation.

To alter database:

ALTER DATABASE dbname CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci; 

See:

• Aaron's comment on this answer How to make MySQL handle UTF-8 properly

• What's the difference between utf8_general_ci and utf8_unicode_ci

• Conversion guide: https://dev.mysql.com/doc/refman/5.5/en/charset-unicode-conversion.html

Original Answer:

MySQL 4.1 and above has a default character set of UTF-8. You can verify this in your my.cnf file, remember to set both client and server (default-character-set and character-set-server).

If you have existing data that you wish to convert to UTF-8, dump your database, and import it back as UTF-8 making sure:

• use SET NAMES utf8 before you query/insert into the database
• use DEFAULT CHARSET=utf8 when creating new tables
• at this point your MySQL client and server should be in UTF-8 (see my.cnf). remember any languages you use (such as PHP) must be UTF-8 as well. Some versions of PHP will use their own MySQL client library, which may not be UTF-8 aware.

If you do want to migrate existing data remember to backup first! Lots of weird choping of data can happen when things don't go as planned!

Some resources:

• complete UTF-8 migration (cdbaby.com)
• article on UTF-8 readiness of php functions (note some of this information is outdated)

Answer 2

To make this 'permanent', in my.cnf:

[client] default-character-set=utf8 [mysqld] character-set-server = utf8 

To check, go to the client and show some variables:

SHOW VARIABLES LIKE 'character_set%'; 

Verify that they're all utf8, except ..._filesystem, which should be binary and ..._dir, that points somewhere in the MySQL installation.