title: How can I join two tables but only return rows that don't match?
body: <p>I have two tables which look like this:</p>
  
  <pre><code>T1:  ID  |  Date  |  Hour  | Interval
  T2:  ID  |  Date  |  Hour
  </code></pre>
  
  <p>I basically need to join these tables when their IDs, dates, and hours match.  However, I only want to return the results from table 1 that do <strong>not</strong> match up with the results in table 2.</p>
  
  <p>I know this seems simple, but where I'm stuck is the fact that there are multiple rows in table 1 that match up with table 2 (there are multiple intervals for any given hour).  I need to return all of these intervals so long as they do not fall within the same hour period in table 2.</p>
  
  <p>Example data:</p>
  
  <pre><code>T1:  1  |  1/1/2011  |  1  |  1
       1  |  1/1/2011  |  1  |  2
       1  |  1/1/2011  |  2  |  1
       1  |  1/1/2011  |  2  |  2
  
  T2:  1  |  1/1/2011  |  1
  </code></pre>
  
  <p>My expected result set for this would be the last two rows from <code>T1</code>.  Can anyone point me on the right track?</p>