title: delete from 3 tables with one query
body: <p>i have 3 tables and i dont want define any foreign key in my tables.
  my tables structure are like below:
  <a href="http://i.stack.imgur.com/NEtNY.jpg" rel="nofollow">tables diagram</a></p>
  
  <p>i have written this query :</p>
  
  <pre><code>delete relativedata, crawls, stored
      from relativedata inner join
           crawls
           on relativedata.crawl_id = crawls.id and
              relativedata.id = ? inner join
           stored
           on stored.crawl_id = crawls.id
  </code></pre>
  
  <p>this query works for me unless one of tables has no records.
  now how can i do this delete in 3 tables in 1 query?</p>