Question

SELECT id, title, keywords, post, img, 
       NULL as device_id, null as mfgr, null as model, null as img 
       FROM blog_posts WHERE MATCH(title, desc_meta, keywords_meta, post) AGAINST('boost')
       UNION ALL
       SELECT NULL, NULL, NULL, NULL, id AS device_id, mfgr, model, img, summary
       FROM device_specs WHERE MATCH(mfgr, model, summary) AGAINST('boost');

考虑上面的查询，两个表没有任何共同之处。这仅用于搜索脚本。我将如何保持与两个组合表的相关性？上述查询有效，但在所有情况下，blog_posts的结果都会显示在device_specs的结果之前。

Answer 1

您想要为每个子查询添加相关性。您可以在没有子查询的情况下执行此操作：

SELECT id, title, keywords, post, img, 
       NULL as device_id, null as mfgr, null as model, null as img,
       MATCH(title, desc_meta, keywords_meta, post) AGAINST('boost') as relevance
FROM blog_posts
WHERE MATCH(title, desc_meta, keywords_meta, post) AGAINST('boost') > 0
UNION ALL
SELECT NULL, NULL, NULL, NULL, id AS device_id, mfgr, model, img, summary,
       MATCH(mfgr, model, summary) AGAINST('boost') as relevance
FROM device_specs
WHERE MATCH(mfgr, model, summary) AGAINST('boost') > 0
ORDER BY relevance;

mysql：union all并按相关性排序？

1 个答案: