这两种登陆验证方法错哪了

这两种登陆验证方法哪里错了
第一种：

PHP code

<!--

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--><?php
$id=$_POST['id'];
$password=$_POST['password'];
 $conn=mysql_connect("localhost","root","root");
 if (!$conn){
 die("连接失败：".mysql_errno());
 }
 mysql_select_db("emp",$conn) or die(mysql_errno());
 mysql_query("set names utf8")or die(mysql_errno());
$sql = "select count(id) from admin where id='".$id."' and password='".md5($password)."'";
$res = mysql_query($sql,$conn);
$num = mysql_num_rows($res);
if($num){
   header("location:empManage.php");
   exit();
}else{
  header("location:login.php?errno=1");
  exit();
}
mysql_free_result($res);
mysql_close($conn);
 
?>

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PHP code

<!--

Code highlighting produced by Actipro CodeHighlighter (freeware)
http://www.CodeHighlighter.com/

--><?php
$id=$_POST['id'];
$password=$_POST['password'];
 $conn=mysql_connect("localhost","root","root");
 if (!$conn){
 die("连接失败：".mysql_errno());
 }
 mysql_select_db("emp",$conn) or die(mysql_errno());
 mysql_query("set names utf8")or die(mysql_errno());
 $sql="select password from admin where id=$id";
 $res=mysql_query($sql,$conn);
 if ($row=mysql_fetch_assoc($res)){
     
 if ($row['password']==md5($password)){
 header("location:empManage.php");

 }
 }
header("location:login.php?errno=1");

mysql_free_result($res);
mysql_close($conn);
?>

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