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<?php $interval = '50:25:10'; $datestring = '2013-01-05 10:55:15'; list($hours, $minutes, $seconds) = explode(':', $interval); $date = new DateTime($datestring); $date->add(new DateInterval('PT'.$hours.'H'.$minutes.'M'.$seconds.'S')); echo $date->format('Y-m-d H:i:s');

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