php generate age based on date of birth

$birthday = '1985-02-01';

$age = date('Y', time()) - date('Y', strtotime($birthday)) - 1;

if (date('m', time()) == date('m', strtotime($birthday))){

if (date('d', time()) > date('d', strtotime($birthday))){

$age++;

}

}elseif (date('m', time()) > date('m', strtotime($birthday))){

$age++;

}

echo $age;

?>

mysql 当前时间-n年计算

select date_add(curdate(), interval -1 year);