I'm trying to learn how to use databases in PHP.
My main html file creates somewhat like a login form. The data which was used as input there is redirected to the PHP file, where it should be printed and also stored in the database.
<?php error_reporting(E_ALL);
        function db_con($data_array){
            $db = mysqli_connect("localhost", "root", "", "form") or die("Fehler beim Herstellen der Verbindung zur Datenbank!");
            mysqli_set_charset($db, 'utf8');
            mysqli_query($db, "
                INSERT INTO 'data'
                (
                    'E-Mail', 'Name', 'Bewertung', 'Kommentar', 'Thema'
                )
                VALUES
                (
                    '".$data_array['E-Mail']."',
                    '".$data_array['Name']."',
                    '".$data_array['Buchbewertung']."',
                    '".$data_array['Kommentar']."',
                    '".$data_array['Lieblingsthema']."'
                )
            ") or die("Fehler beim Schreiben der Datensätze!");
        }
            if(isset($_POST['name'], $_POST['email'], $_POST['rating'], $_POST['comment'], $_POST['interest'])){
            $data_array = array(
                    "Name" => $_POST['name'],
                    "E-Mail" => $_POST['email'],
                    "Buchbewertung" => $_POST['rating'],
                    "Kommentar" => $_POST['comment'],
                    "Lieblingsthema" => $_POST['interest']
                );
            echo "<th colspan='2'>Folgende Daten wurden übermittelt: </th>";
            echo "<br><br>";
                foreach($data_array as $key => $val){
                    echo "<tr><td><b>". $key. ": ". "</b></td><td>". $val. "</td></tr>";
                }
                db_con($data_array);
            }
        ?>
I don't get why it doesn't work. There is no error, but the script stops after mysqli_query (last output: Fehler beim Schreiben der Datensätze!).
Can someone help me why all those data sets won't be stored in the database and how to fix it?
 
     
     
     
    