I have a problem with accessing "comments" table in databases with PHP - php

Question

I have a code that have an access to my database's "comments" table. I did a connection variable and created all the stuff in order to get table. But I when save and refresh the page, it is showing this error below. What's the problem?
<?php
// connection
$connection = mysqli_connect(
$config['db']['server'],
$config['db']['username'],
$config['db']['password'],
$config['db']['name']
);
if ($connection == false)
{
echo 'Error!<br>';
echo mysqli_connect_error();
exit();
}
// comments
$сomments = mysqli_query($connection, "SELECT * FROM `comments` ORDER BY `articles_id` DESC LIMIT 5");
while ($com = mysqli_fetch_assoc($comments))
{
?>
<article class="article">
<div class="article__image" style="background-image: url(https://www.gravatar.com/avatar/<?php echo md5($com['email']); ?>?s=125);"></div>
<div class="article__info">
<?php echo $com['author']; ?>
<div class="article__info__preview"><?php echo mb_substr(strip_tags($com['text']), 0, 100, 'utf-8') . ' ...'; ?></div>
</div>
</article>
<?php
}
?>
Warning: mysqli_fetch_assoc() expects parameter 1 to be mysqli_result, null given in W:\domains\itblog.kg\includes\sidebar.php on line 56 . What is the problem?

Answer 1

The problem is that the query ($comments = mysqli_query(...) is returning a null value. This means that there has been some problem with the query.
Try changing the code like this:
$сomments = mysqli_query($connection, "SELECT * FROM `comments` ORDER BY `articles_id` DESC LIMIT 5");
// start new
if (!$comments) {
echo "Error - " . mysqli_error($connection);
} else
// end new
while ($com = mysqli_fetch_assoc($comments))
{
?>
<article class="article">
...
(Note that you should also surround the whole while loop with braces {}, as it is the else clause, to avoid future errors. But it should work like that.)
The script should report the error it is seeing and it should allow you to fix the query.
Edit - I'd bet that the comments table does not have an articles_id column - probably it should be article_id.