i da questo errore e non riesco a vedere che problema c'e Warning: mysqli_fetch_assoc() expects parameter 1 to be mysqli_result, bool given in C:\xampp\htdocs\pannello\index.php on line 439
<?php $sql_staff="SELECT nome,email,ruolo FROM staff";
$result_staff=mysqli_query($con,$sql_staff);
while($row = mysqli_fetch_assoc($result_staff)) {
?>
<tr>
<td>
<div class="custom-control custom-checkbox">
<input class="custom-control-input checkSingle" id="user_id_1"
required="" type="checkbox"><label class="custom-control-label"
for="user_id_1"></label>
</div>
</td>
<td>
<div class="avatar avatar-md mr-3 mt-1 float-left">
<span class="avatar-letter avatar-letter-a avatar-md circle"></span>
</div>
<div>
<div>
<strong><?php echo $row["nome"]; ?></strong>
</div>
<small> <?php echo $row["email"]; ?></small>
</div>
</td>
<td><span class="r-3 badge badge-success "><?php echo $row["staff"]; ?></span></td>
<td>
<a href="panel-page-profile.html"><i class="icon-eye mr-3"></i></a>
<a href="panel-page-profile.html"><i class="icon-pencil"></i></a>
</td>
</tr>
<?php } ?>