<?php
    require 'conn.php';

    if(ISSET($_POST['res'])){
        $query = $conn->query("SELECT member.mem_id, member.name, GROUP_CONCAT(skill.skill SEPARATOR ', ') skill FROM `member` LEFT JOIN `skill` ON member.mem_id = skill.mem_id GROUP BY member.mem_id");
        while($fetch = $query->fetch_array()){

        echo'
            <tr>
                <td>'.$fetch['name'].'</td>
                <td>'.$fetch['skill'].'</td>
            </tr>';
        }
    }
?>