简而言之,该查询的目标是根据其分数列出所有帖子,该分数是根据日期、观看次数和评分的计算分数计算得出的
SELECT
p.id
, p.date
, p.title
, r.module
, r.module_id
, IFNULL(v.total_views,0) AS views
, r.total_rating AS rating
#the following formula calculates the Score 10*(MAX(points)-(points))/(MAX(points)-MIN(points))
, round((round(10-(((PD.MaxDate-p.date)/(PD.MaxDate-PD.MinDate))*10), 3) + round(10-(((MAX(v.total_views)-v.total_views)/(MAX(v.total_views)-MIN(v.total_views)))*10), 3) + round(10-(((MAX(r.total_rating)-r.total_rating)/(MAX(r.total_rating)-MIN(r.total_rating)))*10), 3))/3, 3) AS Score
FROM posts p
LEFT JOIN ( SELECT ra.module_id
, ra.module AS module
, SUM(ra.ilike) AS total_rating
FROM rates ra
WHERE ra.module = 'posts'
GROUP
BY ra.module_id
) r ON r.module_id = p.id
LEFT JOIN ( SELECT pv.post_id
, SUM(1) AS total_views
FROM posts_views pv
GROUP
BY pv.post_id
) v ON v.post_id = p.id
JOIN (SELECT MIN(date) AS MinDate, MAX(date) AS MaxDate FROM posts) PD
ORDER BY Score DESC
查询的问题在于它只给出 1 行结果,而不是显示所有帖子。
我认为问题在于使用 MAX() 和 MIN() 而不将其与用于获取评级和视图的 SUM() 的 LEFT JOIN 查询分开。
答案是添加以下几行感谢Ivar Bonsaksen:
JOIN ( SELECT MAX(t.total) AS max_views, MIN(t.total) AS min_views FROM ( SELECT COUNT(*) as total FROM posts_views GROUP BY post_id ) t ) mv
JOIN ( SELECT MAX(t.total) AS max_rates, MIN(t.total) AS min_rates FROM ( SELECT COUNT(*) as total FROM rates GROUP BY module_id ) t ) mr
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我来说两句