Select all data from database MySQL not working php but the inserting working

First I have the insertion part here it’s getting data from json file then insert then select

  $mysqli  = new mysqli($servername, $username, $password,$db) or die("Connect failed: 
  %sn". $mysqli  -> error);
  echo "Connected successfully";

 $json = file_get_contents("https://raw.githubusercontent.com/SeteMares/full-stack-test/master/feed.json") ;
    $json = json_decode(  $json,true);
    $content= array();
    $TITLE = array();
    $CONTENT = array() ;
    $MEDIA = array() ;
    $SLUG = array() ;
    $categories = array() ;
    foreach ($json as $key => $value){
      
        $TITLE[] = $json[$key]['title'] ;
      
       
        $CONTENT[] = $json[$key]['content'];
        $MEDIA[] = $json[$key]['media'];
        $SLUG[] = $json[$key]['slug'];
        $categories[] = $json[$key]['categories'];
    }
    
    for($s=0;$s<sizeof($TITLE);$s++){

        $url_string =  $CONTENT[$s][0]['content'];
        $res = urldecode($url_string);
        $Cataggory = $categories[$s]['primary']; 
        echo gettype($Cataggory );
        $slug = $SLUG[$s] ;
        echo gettype($slug );

         $sqlquery = "INSERT INTO `jsondata` (`title`, `slug`, `content`, `categories`, `media`) VALUES (  '$TITLE[$s]',   ? ,   ?, ?,  '$TITLE[$s]' )" ;
         $stmt = $mysqli->prepare($sqlquery);
         $stmt->execute(array($slug,$res,$Cataggory));
       
         
    }

when i select the data it doesn’t work it prints

Fatal error: Uncaught Error: Call to undefined method mysqli_stmt::fetchAll() in C:xampphtdocsfirstphpindex.php:68 Stack trace: #0 {main} thrown in C:xampphtdocsfirstphpindex.php on line 68

this the select code for sure all the code in the same file

     $sqlquery3 = "SELECT 'title'   FROM jsondata  " ;
     $sth = $mysqli->prepare($sqlquery3);
     $sth->execute();
  
     $result = $sth->fetchAll();
     print_r($result);