<?php

 $mysqli = new mysqli("localhost", "***", "***", "***");
 // $mysqli->set_charset('utf8');

 $sql = "SELECT * FROM `posts` as p INNER JOIN posts_contenido as c ON p.id_post = c.id";
 $result = mysqli_query($mysqli, $sql);
 $resultCheck = mysqli_num_rows($result);

 echo "<table>";
 if($resultCheck > 0){

     while($fila = mysqli_fetch_assoc($result)){

         echo "<tr>";
             echo "<td>";
              ?> <img alt ="database_img" src ="<?php echo $fila["url_img"]; ?>" height="100" width="100">
             <?php echo "</td>";
         echo "</tr>";
     }

 }
 echo "</table>";