Multi-byte characters can cause quite a few headaches for the unsuspecting webmaster. Sometimes all you need to do to figure out how to fix the problem is detect which database records have UTF-8 data in them and which ones do not. If you’ve been scanning records manually, stop now. Here’s a quick query to cure your ales:
Return all the rows with multi-byte characters in table posts on field title:
SELECT * FROM posts WHERE LENGTH(title) != CHAR_LENGTH(title)
This does pretty much what it looks like: returns all the rows in the posts table where the title’s character length does not match the title’s length. This works because the
LENGTH function returns the number of bytes in the string, while the
CHAR_LENGTH function returns the number of characters in the string. If the string contains multi-byte characters (individual characters that are made up of more than one byte) like international UTF-8 characters, the two functions will return different numbers and will not be equal, thus including that row in your results.