How to find non utf8 data in mysql
You can check for the existence of (non-)UTF-8 data by comparing byte length to character length on a column, e.g.:

SELECT * FROM MyTable
WHERE LENGTH(MyColumn) &lt;&gt; CHAR_LENGTH(MyColumn)


Multibyte characters will have a greater LENGTH (bytes), so you'll need to look for where that condition isn't met.

Note that MySQL's utf8 character set isn't true Unicode UTF-8 as it only supports a maximum of 3 bytes per character. If your MySQL is later than 5.5.3 you can use utf8mb4 to get 4 bytes per character.