PHP: WordPress – Script(PHP) to convert MySQL collation from utf8mb4 to utf8

If your MYSQL database import fails with Unknown collation: ‘utf8mb4_unicode_ci’ after the latest WordPress update 4.2.2, chances are that you are running a MYSQL server version 5.5.2 or below. With the most recent update, WordPress changed their encoding standard from utf8 to utf8mb4, which is only supported starting with MYSQL server version 5.5.3.