基于dateOfBirth mysql时间戳显示年龄的问题

我有一个用户配置文件的网站。在主页上，我试图展示每个人的个人资料的小摘要。这个摘要包括这个人的名字、性别和年龄。

        <ul>                
            {section name=i loop=$person_list}
                <li><a href="user_detail.php?id={$person_list[i].id}">{$person_list[i].username}, {$person_list[i].gender}, {$age[i]}
            {/section}
        </ul>

我之前使用了foreach循环来遍历它们，但是我还需要索引来显示index.php文件中计算的显示年龄。

if (isset($_GET['name']) && isset($_GET['gender'])) 
{
   $name = $_GET['name'];
   $gender = $_GET['gender'];
} 
else 
{
   $name = "";
   $gender = "";
}
define("PERSONS_PER_PAGE", 10);

if (isset($_GET['offset'])) 
{
    $offset = $_GET['offset'];
} 
else 
{
    $offset = 0;
}

list($person_list, $num_persons) = get_persons($name, $gender, $offset, PERSONS_PER_PAGE);
$ages = array();

for ($i = 0; $i < count($person_list); $i++)
{
    $ages[$i] = age($person_list[$i].$dateOfBirth, time());
}
$smarty = new Smarty;
$smarty->assign("name", $name);
$smarty->assign("gender", $gender);
$smarty->assign("persons_per_page", PERSONS_PER_PAGE);
$smarty->assign("interests", $interests);
$smarty->assign("offset", $offset);
$smarty->assign("num_persons", $num_persons);
$smarty->assign("person_list", $person_list);
$smarty->assign("ages", $ages);
$smarty->display("index.tpl");

不要太担心$offset和PERSONS_PER_PAGE，它们只用于分页。

我的年龄函数是这样的:

function age($birth)
{
   $birth_date = new DateTime();
      $birth_date = $birth;
   $birth_date->setTimestamp($birth);
   $now = time();
   $now_date = new DateTime();
   $now_date->setTimestamp($now);
   $interval = $birth_date->diff($now_date); // $interval is a DateInterval

   $age = $interval->y; // number of years in the interval
   return $age;
}

另外，如果它是相关的;我的get_persons函数如下所示:

function get_persons($name, $gender, $offset, $persons_per_page) 
{
    $connection = mysql_open();
    $query = "SELECT SQL_CALC_FOUND_ROWS id, username, gender, dateOfBirth FROM Person";
    if ($name && $gender) 
    {
        $query .= " WHERE name like '%$name%' AND gender like '%$gender%'";
    }
    $query .= " order by id";
    $query .= " LIMIT $offset, $persons_per_page";
    // print "$query<br>'n";
    $result = mysql_query($query, $connection) or show_error();
    $r = mysql_query("SELECT FOUND_ROWS()", $connection) or showerror();
    $r = mysql_fetch_array($r);
    $num_entries = $r[0];
    $entries = array();
    $person_list = array();
    while ($person = mysql_fetch_array($result)) {
        $person_list[] = $person;
    }
    mysql_close($connection) or show_error();
    return array($person_list, $num_entries);
}

和一个人的表是这样的:

create table if not exists Person
(
  id int not null auto_increment primary key,
  username varchar(10) not null,
  name varchar(40) not null,
  gender varchar(1) not null,
  dateOfBirth timestamp not null,
  email varchar(40) not null
);

这会产生以下错误:

Notice: Undefined variable: dateOfBirth in /net/homes.ict.griffith.edu.au/export/home/s2737451/public_html/wp/labs/lab5/index.php on line 39 Fatal error: Call to a member function setTimestamp() on a non-object in /net/homes.ict.griffith.edu.au/export/home/s2737451/public_html/wp/labs/lab5/includes/defs.php on line 167

提前感谢，我真的需要帮助。