title: sqlzoo track join exercise
body: <p>I've found a great site to practice sql - <a href="http://sqlzoo.net" rel="nofollow">http://sqlzoo.net</a>. my sql is very weak that is why i want to improve it by working on the exercises online.  But i have this one problem that I cannot solve. can you please give me a hand.</p>
  
  <p>3a. Find the songs that appear on more than 2 albums. Include a count of the number of times each shows up.</p>
  
  <p>album(asin, title, artist, price, release, label, rank)
  track(album, dsk, posn, song) </p>
  
  <p>my answer is incorrect as i ran the query. </p>
  
  <pre><code> select a.song, count(a.song) from track a, track b
   where a.song = b.song
  a.album != b.album
  group by a.song
  having count(a.song) &gt; 2
  </code></pre>
  
  <p>thanks in advance! :D</p>