PHP Slider hatası

<?php
$sql = $db->query("SELECT * FROM slayt WHERE lisan='".$lisan."' ORDER BY say ASC");
    $length = count($sql);
    $index = 0;
?>
<div id="main-slide" class="carousel slide" data-ride="carousel">
    <ol class="carousel-indicators">
        <?php for ($i = 0; $i < $length; $i++){ ?>
        <li data-target="#main-slide" data-slide-to="<?php echo $i;?>"<?php echo ($index === $i ? ' class="active"' : '');?>></li>
        <? } ?>
    </ol>
    <div class="carousel-inner">
        <div class="carousel-item<?php echo ($index === $i ? ' active' : '');?>">
            <?php foreach ($length as $i => $item){?>
            <?php echo '<img class="d-block w-100" src="uploads/'.$item['resim'].'" alt="">';?>
            <div class="carousel-caption d-md-block">
                <? if ($item['baslik'] || $item['aciklama'] || $item['link']){?>
                <? if ($item['baslik']){?>
                <h1 class="wow fadeInDown heading" data-wow-delay=".4s">Başlık</h1>
                <? } ?>
                <? if ($item['aciklama']){?>
                <h4 class="fadeInDown wow"  data-wow-delay=".9s">Açıklama</h4>
                <? } ?>
                <? if ($item['link']){?>
                <a href="#" class="fadeInRight wow btn btn-border" data-wow-delay=".6s">Detay</a>
                <? } ?>
                <? } ?>
            </div>
            <? } ?>
        </div>
    </div>
    <a class="carousel-control-prev" href="#main-slide" role="button" data-slide="prev">
        <span class="carousel-control" aria-hidden="true"><i class="lni-chevron-left"></i></span>
        <span class="sr-only">Previous</span>
    </a>
    <a class="carousel-control-next" href="#main-slide" role="button" data-slide="next">
        <span class="carousel-control" aria-hidden="true"><i class="lni-chevron-right"></i></span>
        <span class="sr-only">Next</span>
    </a>
</div>