$group_access_query =  "select forum_id
                       from e_xoops_bbplus_forum_group_access,e_xoops_groups_users_link
                       where group_id=groupid and uid = $userid " ;

$union_access =  "($user_access_query) UNION ($group_access_query) " ;

$posts_select_query= " select post_id
                      from e_xoops_bbplus_posts
                      where forum_id in ($union_access) " ;

 $result_posts=mysql(DBName,$posts_select_query);

$user_access_query  =  "select forum_id
                       from e_xoops_bbplus_forum_access
                       where user_id = $userid " ;