There are several packages that are available for this task:
Pear: http://pear.php.net/package/SQL_Parser (still fairly new)
txtSQL: http://sourceforge.net/projects/txtsql
PHP-SQL-Parse: http://code.google.com/p/php-sql-parser/ (as mentioned by the OP). This seems to be the most robust of these three (certainly the best documented)
