利用PHP实现一个使用邮箱验证激活功能

CREATE TABLE IF NOT EXISTS `t_user` ( 
 `id` int(11) NOT NULL AUTO_INCREMENT, 
 `username` varchar(30) NOT NULL COMMENT '用户名', 
 `password` varchar(32) NOT NULL COMMENT '密码', 
 `email` varchar(30) NOT NULL COMMENT '邮箱', 
 `token` varchar(50) NOT NULL COMMENT '帐号激活码', 
 `token_exptime` int(10) NOT NULL COMMENT '激活码有效期', 
 `status` tinyint(1) NOT NULL DEFAULT '0' COMMENT '状态,0-未激活,1-已激活', 
 `regtime` int(10) NOT NULL COMMENT '注册时间', 
 PRIMARY KEY (`id`) 
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

<form id="reg" action="register.php" method="post"> 
  <p>用户名：<input type="text" class="input" name="username" id="user"></p> 
  <p>密 码：<input type="password" class="input" name="password" id="pass"></p> 
  <p>E-mail：<input type="text" class="input" name="email" id="email"></p> 
  <p><input type="submit" class="btn" value="提交注册"></p> 
</form> 

$username = stripslashes(trim($_POST['username'])); 
$query = mysql_query("select id from t_user where username='$username'"); 
$num = mysql_num_rows($query); 
if($num==1){ 
  echo '用户名已存在，请换个其他的用户名'; 
  exit; 
} 

if(mysql_insert_id()){ 
  $smtpserver = ""; //SMTP服务器，如：smtp.163.com 
  $smtpserverport = 25; //SMTP服务器端口，一般为25 
  $smtpusermail = ""; //SMTP服务器的用户邮箱，如xxx@163.com 
  $smtpuser = ""; //SMTP服务器的用户帐号xxx@163.com 
  $smtppass = ""; //SMTP服务器的用户密码 
  $smtp = new Smtp($smtpserver, $smtpserverport, true, $smtpuser, $smtppass); //实例化邮件类 
  $emailtype = "HTML"; //信件类型，文本:text；网页：HTML 
  $smtpemailto = $email; //接收邮件方，本例为注册用户的Email 
  $smtpemailfrom = $smtpusermail; //发送邮件方，如xxx@163.com 
  $emailsubject = "用户帐号激活";//邮件标题 
  //邮件主体内容 
  $emailbody = "亲爱的".$username."：<br/>感谢您在我站注册了新帐号。<br/>请点击链接激活您的帐号。<br/> 
  <a href='http://www.helloweba.com/demo/register/active.php&#63;verify=".$token."' target= 
'_blank'>http://www.helloweba.com/demo/register/active.php&#63;verify=".$token."</a><br/> 
  如果以上链接无法点击，请将它复制到你的浏览器地址栏中进入访问，该链接24小时内有效。"; 
  //发送邮件 
  $rs = $smtp->sendmail($smtpemailto, $smtpemailfrom, $emailsubject, $emailbody, $emailtype); 
  if($rs==1){ 
    $msg = '恭喜您，注册成功！<br/>请登录到您的邮箱及时激活您的帐号！';   
  }else{ 
    $msg = $rs;   
  } 
} 
echo $msg; 

include_once("connect.php");//连接数据库 
 
$verify = stripslashes(trim($_GET['verify'])); 
$nowtime = time(); 
 
$query = mysql_query("select id,token_exptime from t_user where status='0' and 
`token`='$verify'"); 
$row = mysql_fetch_array($query); 
if($row){ 
  if($nowtime>$row['token_exptime']){ //24hour 
    $msg = '您的激活有效期已过，请登录您的帐号重新发送激活邮件.'; 
  }else{ 
    mysql_query("update t_user set status=1 where id=".$row['id']); 
    if(mysql_affected_rows($link)!=1) die(0); 
    $msg = '激活成功！'; 
  } 
}else{ 
  $msg = 'error.';   
} 
echo $msg;