title: Select values that meet different conditions on different rows?
body: <p>This is a very basic query I can't figure out....</p>
  
  <p>Let's say I have a two column table like this:</p>
  
  <pre><code>userid  |  roleid
  --------|--------
     1    |    1
     1    |    2
     1    |    3
     2    |    1
  </code></pre>
  
  <p>I want to get all distinct userids that have <code>roleids</code> 1, 2 AND 3.  Using the above example, the only result I want returned is <code>userid</code> 1.  How do I do this?</p>