Die richtige Tabelle aus der Datenbank wählen

<?php

include 'main_admin.php'; // DB-Verbindung + html-templates

// Debuggen
error_reporting(-1);
ini_set('display_errors', true);
mysqli_error();
$pdo -> setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); 
error_reporting (E_ALL | E_STRICT);
       
$messages_false =[];
$messages_true = [];

// Prüfe Existenz vom Datensatz

// Variable an die URL angehängt
if (isset($_GET['id'])) {

    if (!empty($_POST)) {
    // POST-Variablen vorhanden? - sonst nimm leeren Wert
    $id                     = isset($_POST['id']) ? $_POST['id'] : NULL;  
        $db_charset           = isset($_POST['db_charset']) ? $_POST['db_charset'] : '';
    $mail_from               = isset($_POST['mail_from']) ? $_POST['mail_from'] : '';
    $mail_address            = isset($_POST['mail_address']) ? $_POST['mail_address'] : '';
    $account_activation    = isset($_POST['account_activation']) ? $_POST['account_activation'] : '';
    $activation_link         = isset($_POST['activation_link']) ? $_POST['activation_link'] : '';

      if (empty($messages_false)) {
        // Aendere den Datensatz (record)
            $stmt = $pdo->prepare('UPDATE admin SET id = ?, db_charset = ?, mail_from = ?, mail_address = ?, account_activation = ?, activation_link = ? WHERE id = ?');        
            $stmt->execute([$id, $db_charset, $mail_from, $mail_address, $account_activation, $activation_link, $_GET['id']]);         
            $messages_true[] = 'Datensatz ist gespeichert';     
        }    
    }    
    // Get the account from the admin table
    $stmt = $pdo->prepare('SELECT db_charset, mail_from, mail_address, account_activation, activation_link FROM admin WHERE id = ?'); 
    $stmt->execute([$_GET['id']]);
    $account = $stmt->fetch(PDO::FETCH_ASSOC);
    
        if (!$account) {
            exit('Kein Kontakt mit dieser id');
        }  
}  
 else {
       exit('No ID specified!');
}

?>


<?=template_admin_header($title)?>

<h2>Einstellungen</h2>

<div class="content-block">
    <form action="settings_admin_new.php?id=<?=$account['id']?>" method="post" <!-- class="form responsive-width-100"> -->        <!-- dbf -->
       <div class="fl">
                <label for="db_charset">db_charset</label><br>                    
                <input type="text" name="db_charset" value="<?php echo isset($account['db_charset']) ? htmlspecialchars($account['db_charset']) : ''; ?>" />
    </div>    
    <div class="fl">
                <label for="mail_from">Email von</label><br>                    
                <input type="text" name="mail_from" value="<?php echo isset($account['mail_from']) ? htmlspecialchars($account['mail_from']) : ''; ?>" />
    </div>    
    <div class="fl">
                <label for="mail_address">Email-Adresse</label><br>                    
                <input type="text" name="mail_address" value="<?php echo isset($account['mail_address']) ? htmlspecialchars($account['mail_address']) : ''; ?>" />
    </div>    
    <div class="fl">
                <label for="account_activation">Account Activation</label><br>                    
                <input type="text" name="account_activation" value="<?php echo isset($account['account_activation']) ? htmlspecialchars($account['account_activation']) : ''; ?>" />
    </div>    
    <div class="fl">
                <label for="activation_link">Activation Link</label><br>                    
                <input type="text" name="activation_link" value="<?php echo isset($account['activation_link']) ? htmlspecialchars($account['activation_link']) : ''; ?>" />
    </div>      
        <div class="submit-btns">
            <input type="submit" name="submit" value="Submit">
        </div>
    </form>
</div>

<?=template_admin_footer()?>