<h2 style="text-align:center;">Change your password</h2>
<br>
<br>
<form action="" method="post">

<table align="center" width="600" height="150">
    <tr>
        <td align="right"><b>Enter current password:</b></td>
        <td><input type="password" name="current_pass" required></td>
    </tr>

    <tr>
        <td align="right"><b>Enter new password:</b></td>
        <td><input type="password" name="new_pass" required></td>
    </tr>

    <tr>
        <td align="right"><b>Confirm your new password:</b></td>
        <td><input type="password" name="new_pass_again" required></td>
    </tr>

    <tr align="center">
    <td colspan="8"><input type="submit" name="change_pass" value="Change password"/></td>
    </tr>

</table>

</form>

<?php

include ("includes/db.php");

if(isset($_POST['change_pass'])){

    $user = $_SESSION['customer_email'];

    $current_pass = $_POST['current_pass'];
    $new_pass = $_POST['new_pass'];
    $new_again = $_POST['new_pass_again'];

    $sel_pass = "select * from customers where customer_pass='$old_pass'
    AND customer_email='$user'";

    $run_pass = mysqli_query($con, $sel_pass);

    $check_pass = mysqli_num_rows($run_pass);

    if($check_pass==0){

        echo "<script>alert('Your current password is wrong!')</script>";
        exit();

    }

    if($new_pass!=$new_again){

        echo "<script>alert('ERROR! Insert new password again')</script>";
        exit();

    }

    else {

        $update_pass = "update customers set customer_pass='$new_pass'
        where customer_email='$user'";

        $run_update = mysqli_query($con, $update_pass);

        echo "<script>alert('Your password has been updated!')</script>";
        echo "<script>window.open('my_account.php','_self')</script>";

    }

}

?>