Can I use "u.userpic" there?
$sql = "SELECT c.comment_id, c.image_id, c.user_id, c.user_name AS comment_user_name, c.comment_headline, c.comment_text, c.comment_ip, u.userpic, c.comment_date".get_user_table_field(", u.", "user_level").get_user_table_field(", u.", "user_name").get_user_table_field(", u.", "user_email").get_user_table_field(", u.", "user_showemail").get_user_table_field(", u.", "user_invisible").get_user_table_field(", u.", "user_joindate").get_user_table_field(", u.", "user_lastaction").get_user_table_field(", u.", "user_comments").get_user_table_field(", u.", "user_homepage").get_user_table_field(", u.", "user_icq").get_user_table_field(", u.", "user_id").$additional_sql."