int mktime ([ int $hour = date("H") [, int $minute = date("i") [, int $second = date("s") [, int $month = date("n") [, int $day = date("j") [, int $year = date("Y") [, int $is_dst = -1 ]]]]]]] )
$lyj_1 = "2016-12-22 16:19:02";
$lyj_2 = explode(" ", $lyj_1);
$lyj_3 = explode("-",$lyj_2[0]);
$lyj_4 = explode(":",$lyj_2[1]);
$str = mktime($lyj_4[0],$lyj_4[1],$lyj_4[2],$lyj_3[1],$lyj_3[2],$lyj_3[0]);
echo $str;
// 1482391142
echo "<br/><br/><br/>";
$times = date("Y-m-d H:i:s", $str);
echo $times;