How to calculate difference between two values in two different rows
<p>I have some tables in postgresql database  with historical data such as following sample: </p>

<pre><code> log_id  |       login_time    |       logout_time       
----------+---------------------+---------------------
12885913 | 2016-03-01 05:10:59 | 2016-03-01 09:40:46
12886931 | 2016-03-01 09:41:51 | 2016-03-01 12:44:49
12887276 | 2016-03-01 12:45:54 | 2016-03-01 13:42:18
</code></pre>

<p>I want to calculate difference between logout_time of each row with next login_time and save it as login time interval. This table is result of python script that connect to postgresql 9.1 and extract these data from other tables and I want to find a solution with python for this issue.</p>