Just installed the latest XAMP from ApacheFriends.org, and received this error.
To fix, edit php.ini which is in XAMP home /php
unremmark (remove the two ;;) from the line that contains ;;extension=php_mysql.dll
Now while I appreciate the work done on this free project, AMP does stand for Apache PHP-MYSQL,
one would assume that functionality would be “out of the box”. – silly me