网站不会在使用PHP的输入中显示可变内容

Question

该站点应在输入中显示变量内容。变量用数据库中的行填充。即使数据库中有数据，输入也为空。

此外，在“打开请求”下，它应显示数据库中彼此下方的所有用户名。 但是该网站显示“ else”消息。

    <form action="" method="post">
        <input type="text" id="AantalPer" name="aantalPer" value="<?php echo $request_passagiers; ?>" readonly/>
        <input type="text" id="MinLaad" name="minLaad" value="<?php echo $request_laadruimte ?>" readonly/>
        <input type="text" id="Mobiel" name="mobiel" value="<?php echo $request_mobiel; ?>" readonly/>

        <input type="text" id="Datum" name="datum" value="<?php echo $request_datum; ?>" readonly/>
        <input type="text" id="Tijd" name="tijd" value=" " readonly/>
        <input type="text" id="Email" name="email" value="<?php echo $request_email; ?>" readonly/>
        <input type="submit" name="accept" class="Accept" value="Accepteren"/>
        <input type="submit" name="decline" class="Decline" value="Weigeren"/>        
    </form>

对于请求：

<h3>Open requests</h3>```
            <?php
            $query = "SELECT 
                        taxi_aanvraag.Gebruikersnaam, 
                        taxi_aanvraag.klantid,
                        taxi_aanvraag.minimale_laadruimte, 
                        taxi_aanvraag.passagiers, 
                        taxi_aanvraag.lattitude, 
                        taxi_aanvraag.longitude, 
                        taxi_aanvraag.datum,
                        klant.chauffeurid,
                        klant.Gebruikersnaam,
                        klant.naam,
                        klant.mobiel,
                        klant.email
                        FROM taxi_aanvraag
                        INNER JOIN klant ON
                        taxi_aanvraag.Gebruikersnaam = klant.Gebruikersnaam";

                        if($result = mysqli_query($conn, $query)) {
                            $row_count = mysqli_num_rows($result);
                            if($row_count > 0) {
                                while ($row = mysqli_fetch_assoc($result)) {
                                $request_latitude = $row['lattitude'];
                                $request_longitude = $row['longitude'];
                                $request_passagiers = $row['passagiers'];
                                $request_laadruimte = $row['minimale_laadruimte'];
                                $request_email = $row['email'];
                                $request_mobiel = $row['mobiel'];
                                $request_datum = $row['datum'];
                                $request_gebruikersnaam = $row['Gebruikersnaam'];
                                $request_klantid = $row['klantid'];

                                echo '<p>'. $request_gebruikersnaam .'</p>';
                                }
                            }
                            else {
                            echo '<p>There are no existing requests.</p>';
                            }
                        }