title: mysql string conversion return 0
body: <p>why <code>select 'aaa' =0</code> return 1 (TRUE)
  if i have a table like</p>
  
  <pre><code>userid | pass
  
  user1  | pas1
  </code></pre>
  
  <p>if I query : </p>
  
  <pre><code>select from table where userid = 0 and pass =0 
  </code></pre>
  
  <p>it gives me all the rows?</p>