title: Testing if a site is vulnerable to Sql Injection
body: <p>I was reading about sql injection and i understand how it works if there is a form where the user can enter his username and login. What i dont get is how websites without a login page can be vulnerable to sql injection.</p>
  
  <p><a href="http://thecybersaviours.com/how-to-find-out-if-a-website-is-vulnerable-to-sql-injection" rel="noreferrer">http://thecybersaviours.com/how-to-find-out-if-a-website-is-vulnerable-to-sql-injection</a></p>
  
  <p>It says just append a ' or ''=' to test it. I dont understand how this helps to determine whether an error exists. Where is the query being constructed at all.</p>