What is with all this comment spam, it's new they just type a link to their page quoting your post. :(
SQL Injection is a very severe vulnerability. Here is three examples from Flenov.net:
http://www.flenov.net/blog.php?catid=1
http://www.flenov.net/blog.php?catid=46
http://www.flenov.net/blog.php?catid=47