If you use XAMPP for dev work on your Mac at home, and updated your OS to Yosemite, you may be temporarily distressed when you find that your MySQLd doesn’t start up. The fix is fairly simple.

Edit /Applications/XAMPP/xamppfiles/xampp. (You may have to use sudo to do this.)

Look for:

$XAMPP_ROOT/bin/mysql.server start > /dev/null &

And add unset DYLD_LIBRARY_PATH on top of it. It should look like:

unset DYLD_LIBRARY_PATH
$XAMPP_ROOT/bin/mysql.server start > /dev/null &

Restart MySQLd and you it should work.