查找 SQL 查询返回的空值

Question

I am calling an SQL statement which selects everything from a view. There might be some null values returned, I would like to find them and highlight them in the HTML document. This is my code so far. How can I find the empty columns (which can be seen in the picture) so I could highlight them with CSS?

Thanks.

<?php 
require_once '../includes/header.php'; 

$sql = $conn->prepare("SELECT * FROM vw_allpropertiesandagents ORDER BY Price");
$sql->execute();
?>

<section class="main-sec">
<h1>All Agents and All properties</h1>
<p>The properties even the ones that have no agents assigned to them are displayed</p>
<table class ='dba-table'>
    <tr>
        <th>Property Id</th>
        <th>Full Address</th>
        <th>Price</th>
        <th>Property Agent Id</th>
        <th>Agent Id</th>
        <th>For</th>
        <th>Property Type</th>
    </tr>
<?php while ($row = $sql->fetch()){ ?>
    <tr>
    <?php 

    foreach ($row as $value){ ?>
        <td><?php echo $value?></td>
    <?php } ?>
    </tr>


    <?php } ?>
</table>
</section>


<?php 
require_once '../includes/footer.php'; 

?>

This is the HTML output ] 1

Answer 1

If I understand correctly you are looking for something like this:

<?php foreach ($row as $value): ?>
   <?php if($value === null): ?>
      <td style="background-color: red;">Empty</td>
   <?php else: ?>
      <td><?= $value ?></td>
   <?php endif; ?>
<?php endforeach; ?>

Please be aware that this code is vulnerable to XSS because you are not escaping the data when echo'ing. I would recommend to only use this code locally for learning purposes.

There are some excellent articles on the internet, which you can read to learn how to prevent XSS injection.