title: mySQL auto increment doesn't adjust to changes in database
body: <p>So I have auto increment on my primary key. I was under the impression that if I have:</p>
  
  <p>1.
  2.
  3.
  4.</p>
  
  <p>And remove two, I won't end up with this:</p>
  
  <p>1.
  3.
  4.</p>
  
  <p>But rather:</p>
  
  <p>1.
  2.
  3.</p>
  
  <p>Is this not the function of auto increment? If so, what is this I'm trying to achieve, and how can I do it?</p>