ช่วยดูหน่อยครับมันขึ้นmysqli_fetch_array() expects parameter 1 to be mysqli_result, boolean given in

โค๊ดครับ

<?php
include_once('connectdb.php');
 
 $sql = "SELECT * FROM airline";
 $result = mysqli_query($conn,$sql);
 while($data = mysqli_fetch_array($result)){
?>
          <div class="col-md-4">
            <div class="intro ftco-animate">
                    <img src="images/<?=$data['img'];?>" width="300">
              <h3><span>01</span><?php echo $data['name'];?></h3>
              <p><?php echo $data['details'];?></p>
                 </div>
          </div>
                <? }?>