title: Why does the minus operator give different result than the TIMESTAMPDIFF() function in mysql?
body: <p>Since TIMESTAMP in mysql is stored as a 32bit value representing the time interval from 1970-jan-1 0:00:00 in seconds, I assumed that using minus (-) operator on TIMESTAMP values would give the difference of these values in seconds. Actually not:</p>
  
  <pre><code>+---------------------------------------------------------------------+
  | TIMESTAMP("2010-04-02 10:30:00") - TIMESTAMP("2010-04-02 10:29:59") |
  +---------------------------------------------------------------------+
  | 41.000000                                                           |
  +---------------------------------------------------------------------+
  1 row in set (0.05 sec)
  
  mysql&gt; select timestampdiff(SECOND,TIMESTAMP("2010-04-02 10:30:00"),TIMESTAMP("2010-04-02 10:29:59"));
  +-----------------------------------------------------------------------------------------+
  | timestampdiff(SECOND,TIMESTAMP("2010-04-02 10:30:00"),TIMESTAMP("2010-04-02 10:29:59")) |
  +-----------------------------------------------------------------------------------------+
  | -1                                                                                      |
  +-----------------------------------------------------------------------------------------+
  
  mysql&gt; select TIMESTAMP("2010-04-02 10:30:00") - TIMESTAMP("2010-04-02 10:30:01") ;
  +---------------------------------------------------------------------+
  | TIMESTAMP("2010-04-02 10:30:00") - TIMESTAMP("2010-04-02 10:30:01") |
  +---------------------------------------------------------------------+
  | -1.000000                                                           |
  +---------------------------------------------------------------------+
  
  +---------------------------------------------------------------------+
  | TIMESTAMP("2010-04-02 10:30:00") - TIMESTAMP("2010-04-02 10:31:00") |
  +---------------------------------------------------------------------+
  | -100.000000                                                         |
  +---------------------------------------------------------------------+
  </code></pre>
  
  <p>It seems like one minute difference is 100 instead of 60.</p>
  
  <p>Why is this?</p>