$timestamp = strtotime($start_time);                

$sta_time=date("Y-m-d H:i:s",mktime(0,0,0,date('m', $timestamp),date('d', $timestamp),date('Y', $timestamp)));                $end_time=date("Y-m-d H:i:s",mktime(0,0,0,date('m', $timestamp),date('d', $timestamp)+1,date('Y', $timestamp))-1);