title: Insert data from column to another different table column with modifying in PSQL
body: <p>I have a table called log that contains a column called time which is a time stamp with time zone, I wanna remove the time and only leave the date then put the modifying result in another column called day in a table called error.
  For example if the the <strong>time column in the log table</strong> looks like this <strong>the day column in the error table</strong> should look like this.</p>
  
  <pre><code> |---------- time --------|      |-----day-----| 
   | 2016-07-01 09:00:00+02 |      | 2016-07-01  |
   | 2016-07-01 09:00:47+02 |      | 2016-07-01  |
   | 2016-07-01 09:00:34+02 |      | 2016-07-01  | 
  </code></pre>