How to add time element to open date and close date when adding a quiz
You can convert it to an array using the php function substr 

// lets assume $date = Array ('quiz_open' =&gt; '2016-05-12 21:17');

$year = substr($date['quiz_open'], 0, 4); // grabs 2016
$month = substr($date['quiz_open'], 5, 2); // grabs 05
$day = substr($date['quiz_open'], 8, 2); // grabs 12

$date = array ('quiz_close' =&gt; array (
                                'day' =&gt; $day,
                                'month' =&gt; $month,
                                'year' =&gt; $year,
                                     )
              );