Log in log out session php

I have here the code of my login and logout can you guys check if the session I placed is correct?

Login code:

<?php
session_start();

header("Cache-Control: no-store, no-cache, must-revalidate, max-age=0");
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache");
header('Content-Type: text/html');

$connection = mysql_connect("localhost", "root", "");
$db = mysql_select_db("store_data", $connection);

if(isset($_POST['login'])){
    $admin=$_POST['user'];
    $pass=$_POST['pass'];
    $select_user = mysql_query("SELECT admin_name FROM admin");
    $select_pass = mysql_query("SELECT admin_pass FROM admin");
    $result_1 = mysql_fetch_assoc($select_user);
    $result_2 = mysql_fetch_assoc($select_pass);

    if($admin !=$result_1['admin_name'] || $pass!=$result_2['admin_pass']){
        echo "<script >alert('Invalid password or username')</script>";
        header("refresh:0; url=administrator.php" );
    }

Logout code:

<?php

session_destroy();
header("Location: administrator.php");

?>

Copyright License：
Author:「drandreb andal」,Reproduced under the CC 4.0 BY-SA copyright license with link to original source & disclaimer.
Link to：https://stackoverflow.com/questions/33258130/log-in-log-out-session-php