text: SELECT MAX(article_id) + 1 as ID FROM article;
  SELECT * FROM tag where tag_category=1;SELECT * FROM tag where tag_category=2;
  INSERT INTO tag (tag_name,tag_category) VALUES ('AI',1);
  DELETE FROM category WHERE ctg_id=3;DELETE FROM tag WHERE tag_category IS NULL;
  SELECT
  	( @rownum := @rownum + 1 ) AS no,
  	a.*,
  	c.ctg_name,
  	t.*
  FROM
  	article a
  	LEFT JOIN category c ON a.article_ctg = c.ctg_id
  	LEFT JOIN articles_tags_relation r ON r.relation_article = a.article_id
  	LEFT JOIN tag t ON r.relation_tag = t.tag_id,
  	(SELECT @rownum := 0) row
  GROUP BY
  	a.article_id
  ORDER BY
  	a.article_updatetime DESC;
  