Get Featured Image via direct sql query

$Featured_image = $wpdb->get_results("
    SELECT p.*
      FROM net_5_postmeta AS pm
     INNER JOIN net_5_posts AS p ON pm.meta_value=p.ID 
     WHERE pm.post_id = $da_id
       AND pm.meta_key = '_thumbnail_id' 
     ORDER BY p.post_date DESC 
     LIMIT 15
",'ARRAY_A');