title: SQL Work out the average time difference between total rows
body: <p>I've searched around SO and can't seem to find a question with an answer that works fine for me. I have a table with almost 2 million rows in, and each row has a MySQL Date formatted field.</p>
  
  <p>I'd like to work out (in seconds) how often a row was inserted, so work out the average difference between the dates of all the rows with a SQL query.</p>
  
  <p>Any ideas?</p>
  
  <p>-- EDIT --</p>
  
  <p>Here's what my table looks like</p>
  
  <pre><code>id, name, date (datetime), age, gender
  </code></pre>