Usually an easy way to check if a site uses SQL is if they have things such as <a href="http://target.com/index.php?id=1">http://target.com/index.php?id=1</a> or something similar to that in their url so to check just add something like <a href="http://target.com/index.php?id=1'">http://target.com/index.php?id=1'</a> and 1=0-- this is just making the statement always return false which as long as the page is using SQL will not output correctly.