How to remove all html tag from WordPress post_content Using SQL ?

 
$dbname = DB_NAME;
$servername = DB_HOST ;
$username = DB_USER ;
$password = DB_PASSWORD ;
try {
    $conn = new PDO(“mysql:host=$servername;dbname=$dbname”, $username, $password);
    // set the PDO error mode to exception
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    echo “Connected successfully”;
$sql=”SELECT  post_content,ID  FROM wp_posts WHERE  post_type=’resources’  AND post_status=’publish'”;
 
$page=$conn->prepare($sql);
$page->execute();
$row = $page->fetchAll(PDO::FETCH_ASSOC);
foreach($row as $values)
{
$post_content=clean(strip_tags($values['post_content']));
$id=$values[‘ID’];
 
if(($id>0)&&($post_content!=”))
{
$sql1=”UPDATE wp_posts SET  post_content='”.$post_content.“‘ WHERE post_type=’resources’ AND post_status=’publish’ AND ID='”.$id.”‘”;
$page=$conn->prepare($sql1);
$page->execute();
}
 
}
}
catch(PDOException $e)
 {
    echo “Connection failed: ” . $e->getMessage();
 }
function clean($string) {
   //$string = str_replace(‘ ‘, ‘-‘, $string); // Replaces all spaces with hyphens.
 
   return preg_replace(‘/[^A-Za-z0-9 \-]/’, ”, $string); // Removes special chars.
}

How to load more content, while scrolling page down with jquery ?

HTML PART

<ul class="grid effect-2" id="grid">
<li style="width:100%;">
<div class="col-sm-3 col-md-3 col-xs-12 col-lg-3 pb-4">
<img src="https://www.tutorialshore.com/wp-content/uploads/2016/09/LG-G6-smartphone-150x150.jpg" alt="lg-g6-smartphone" width="150" height="150" class="alignnone size-thumbnail wp-image-128" />
</div ></li>
<li style="width:100%;">
<div class="col-sm-3 col-md-3 col-xs-12 col-lg-3 pb-4">
<img src="https://www.tutorialshore.com/wp-content/uploads/2016/09/LG-G6-smartphone-150x150.jpg" alt="lg-g6-smartphone" width="150" height="150" class="alignnone size-thumbnail wp-image-128" />
</div ></li>
</ul>

Jquery Script 

jQuery(window).on('scroll', function(responseTxt, statusTxt, xhr) {
var total_li=jQuery('ul#grid li').length;
if((total_li>0)&&(k>0))
{
var wS = jQuery(this).scrollTop();
var l_total=jQuery('ul#grid li').length*50;
if (wS > l_total){
k=0;
let req_page = 'https://www.tutorialshore.com/api.php?name=newpicture';
let page_ct = counter += 1;
req_page = req_page+'&page_limit='+page_ct;
var content;
jQuery.get(req_page, function(data){
content= data;
k=1;
jQuery('#grid').append(content);

new AnimOnScroll( document.getElementById( 'grid' ), {
minDuration : 0.4,
maxDuration : 0.7,
transitionDuration : 0.2,
viewportFactor : 0.2
});
});
}
}
});