Record user login and logout timing In php,,i am getting login and logout time, but in database userid alway show 0,

<?php
include_once("database-config.php");
      session_start();
      

      $strDateNew=date("d-m-Y H:i:s");
       if ($_SESSION['userid']){

      $queryString = "update admin set outtime=NOW()  WHERE  userid = '$_SESSION[userid]' and intime='$strDateNew' ";
        $result1=mysql_query($queryString)OR die("Error:".mysql_error());
        echo "$queryString";
        }
        if(session_destroy())
   {
    header('Location: index.php');
}
   
      
?>here  userid passes 0 to database ,i want userid so that in every month i dispay userlogin and logout time  so kindly help me
here is also my authentic.php
<?php ini_set('display_errors', '1'); ?>  
<?php
include_once("database-config.php");
 
  session_start();
 $username=$_POST['username'];
 $password=$_POST['password'];
 $userid=$_POST['userid'];
 $username=stripcslashes($username);
 $username=mysql_real_escape_string($username);
 $username=htmlspecialchars($username);
 
 $password=stripcslashes($password);
 $password=mysql_real_escape_string($password);
 $password=htmlspecialchars($password);
 $sql="SELECT * FROM userregister  WHERE username='$username' and password='$password'";
$result=mysql_query($sql)OR die("Error:".mysql_error());

 $row=mysql_num_rows($result);
$userinfo=mysql_fetch_assoc($result);
$_SESSION['userid']=$userid;
 $role=$userinfo['role'];
 
 if($row==1){

  $_SESSION['login_user']=$username;
  $_SESSION['role']=$role;
  $_SESSION['userid']=$id;
  $_SESSION['username']=$username;
  $_SESSION['intime']=$intime;
 
  $queryString = "INSERT INTO admin set userid='$userid' and intime='$NOW()' ";
  $result1=mysql_query($queryString)OR die("Error:".mysql_error());
 $row1=mysql_num_rows($result1);
  if($role=='admin'){
   
   
  header('location:admin.php');
  }
  if($role=='user'){
   
  header('location:user.php');
  }
  if($role=='moderator'){
  header('location:moderator.php');
  }
   
   
 }else{
  echo "No User Found by Given Information";
 }
 
 
?>