SELECT id, title, content, photo_small1, DATE_FORMAT(pub_date, '%Y/%m') AS yearMonth, DAY(pub_date) AS thisDay, tag
FROM news WHERE orders > 0 AND CURRENT_TIMESTAMP() BETWEEN IFNULL(start_date, CURRENT_TIMESTAMP()) AND IFNULL(end_date, CURRENT_TIMESTAMP()) 
ORDER BY orders, pub_date DESC

Unknown column 'tag' in 'field list'