title: SQL- Return rows after nth occurrence of event per user
body: <p>I'm using postgreSQL 8.0 and I have a table with user_id, timestamp, and event_id.</p>
  
  <p>How can I return the rows (or row) after the 4th occurrence of event_id = someID per user?</p>
  
  <pre><code>|---------------------|--------------------|------------------|
  |      user_id        |     timestamp      |     event_id     |
  |---------------------|--------------------|------------------|
  |          1          |  2020-04-02 12:00  |        11        |
  |---------------------|--------------------|------------------|
  |          2          |  2020-04-02 13:00  |        11        |
  |---------------------|--------------------|------------------|
  |          2          |  2020-04-02 14:00  |        99        |
  |---------------------|--------------------|------------------|
  |          2          |  2020-04-02 15:00  |        11        |
  |---------------------|--------------------|------------------|
  |          2          |  2020-04-02 16:00  |        11        |
  |---------------------|--------------------|------------------|
  |          2          |  2020-04-02 17:00  |        11        |
  |---------------------|--------------------|------------------|
  |          2          |  2020-04-02 17:00  |        11        |
  |---------------------|--------------------|------------------|
  </code></pre>
  
  <p>Ie if event_id = 11, I would only want the last row in the table above.</p>