Php & Session after login to page ← (PHP, MySQL)

one text

I have created login page which after user name and pass word is accessing my other pages. But problem is when I am creating session for other pages which I do n't want to be accused without login. I am directed from login page to login again

<?php
    session_start();
    if(isset($_POST['submit'])){
        $user=$_POST['user'];
        $password=$_POST['password'];
        $query="SELECT * FROM login WHERE user='$user' && password='$password'";
        $data=mysqli_query($db_conn,$query);
        $total=mysqli_num_rows($data);  

        if($total==1)   {
            echo("Login Sucessfull");
            $_SESSION['log']=1;
            header("refresh:3;url=customer_data_ie.php");   
        }
        elseif($total==is_null()){
            echo("Invalid User");
            header("refresh:2;url=login_page_crm.php");
        }
        else{
            echo "Invalid User";
        }
    }
    ?>
<?php
session_start();

if(isset($_SESSION['user'])){
    header("location:login_page_crm.php");
}else{
    header("location:customer_data_ie.php");
}