Question

I’m learning PHP with SQL statments, but I’ve encountered a problem when trying to create a delete button.

The problem is that nothing is happening when i’m pressing the “delete” button.
The query is functioning properly, it gets the correct userid from the loop.

<?php
        require_once 'db_connect.php';

        $select = "SELECT * FROM Users";
        $result = mysqli_query($dbc, $select) or die('could not query database');


        while ($row = mysqli_fetch_assoc($result)) {

            echo '
            <tr>
                <td>' . $row['userid'] . '</td>
                <td>' . $row['fnamn'] . ' ' . $row['enamn'] . '</td>
                <td>' . $row['username'] . '</td>
                <td>' . $row['email'] . '</td>
                    <td>' . '<form action="" method="post">
                            <input type="button" name="delete" value="Radera" />
                        </form>' . '</td>

            </tr>';

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

                $userid = $row['userid'];

                $delete = "DELETE FROM Users WHERE userid = '$userid' ";
                $result = mysqli_query($dbc, $delete) or die('could not query database');
            }
        }

        mysqli_close($dbc);
        ?>

Answer 1

You need to:

1. Place your if (isset($_POST['delete'])) statement outside and
   before your while loop.
2. Have some way of knowing which row your deleting (maybe with a
   hidden input).

Something like this:

<?php
require_once 'db_connect.php';

if(isset($_POST['delete']) && isset($_POST['user_id'])) {
    $userid = $_POST['user_id'];

    $delete = "DELETE FROM Users WHERE userid = '$userid' ";
    $result = mysqli_query($dbc, $delete) or die('could not query database');
}

$select = "SELECT * FROM Users";
$result = mysqli_query($dbc, $select) or die('could not query database');

while ($row = mysqli_fetch_assoc($result)) {
    echo '
    <tr>
        <td>' . $row['userid'] . '</td>
        <td>' . $row['fnamn'] . ' ' . $row['enamn'] . '</td>
        <td>' . $row['username'] . '</td>
        <td>' . $row['email'] . '</td>
        <td>' . '<form action="" method="post">
            <input type="hidden" name="user_id" id="user_id" value="'.$row['userid'].'" />
            <input type="submit" name="delete" id="delete" value="Radera" />
        </form>' . '</td>
    </tr>';
}

mysqli_close($dbc);
?>

I wouldn’t advise you to just insert $_POST['user_id'] directly into your query like above; you’ll want to read up on prepared statements