title: Remove close (in time) rows from the table
body: <p>I have an SQL table Tb like:</p>
  
  <pre><code>ID      EventDate
  18179   2014-11-12 10:18:08.0
  18179   2014-12-12 09:41:02.0
  18179   2014-12-12 10:26:03.0
  18179   2014-12-12 10:28:00.0
  18179   2014-12-12 11:17:36.0
  18179   2014-12-12 12:17:45.0
  18179   2014-12-12 12:17:56.0
  262070  2014-11-12 11:30:00.0
  262070  2014-11-12 11:33:26.0
  262070  2014-12-12 10:17:19.0
  262070  2014-12-12 11:33:26.0
  </code></pre>
  
  <p>I need to do a grid removing for every ID: create new table by removing those rows from Tb that laid within an hour starting from the most recent.
  In that particular case my table Tb_new should looks like</p>
  
  <pre><code>ID      EventDate
  18179   2014-11-12 10:18:08.0
  18179   2014-12-12 09:41:02.0
  18179   2014-12-12 11:17:36.0
  18179   2014-12-12 12:17:56.0
  262070  2014-11-12 11:33:26.0
  262070  2014-12-12 10:17:19.0
  262070  2014-12-12 11:33:26.0
  </code></pre>
  
  <p>Original table is huge (millions or rows, 100K+ of ID's).
  Can somebody, please, help me to find the fastest way to do it on SQL? </p>