Question

我没有完全理解为什么排序与＃34; ORDER BY平均值，投票DESC＆＃34;，因为我需要最高的平均值和投票从上到下，但是DESC没有解决什么问题。我在var_dump http://pastie.org/private/b05smuh0fvw72wwp2w1zq最高entrie的结果是在底部，但我需要从顶部开始并且到底部。

SELECT c.*, r.votes, c.total_comments,
       ROUND(sumrate / votes) AS average
FROM catalog c LEFT JOIN
     (SELECT r.object_id, COUNT(*) as votes, SUM(r.rate) as sumrate
      FROM ratings r
      GROUP BY r.object_id
     ) r
     ON r.object_id = c.catalog_id LEFT JOIN
     (SELECT c.catalog_id, COUNT(*) as total_comments
      FROM comments c
      GROUP BY c.catalog_id
     ) c
     ON c.catalog_id = c.catalog_id
GROUP BY c.catalog_id
ORDER BY average, votes DESC;

Answer 1

因为您可以定义每个列的顺序，而不仅仅是order by。默认值为ASC。

您的订单

ORDER BY average, votes DESC

自动转入

ORDER BY average ASC, votes DESC

但你正在寻找

ORDER BY average DESC, votes DESC

Answer 2

您需要为这两列指定DESC。否则默认为ASC

SELECT c.*, r.votes, c.total_comments,
       ROUND(sumrate / votes) AS average
FROM catalog c LEFT JOIN
     (SELECT r.object_id, COUNT(*) as votes, SUM(r.rate) as sumrate
      FROM ratings r
      GROUP BY r.object_id
     ) r
     ON r.object_id = c.catalog_id LEFT JOIN
     (SELECT c.catalog_id, COUNT(*) as total_comments
      FROM comments c
      GROUP BY c.catalog_id
     ) c
     ON c.catalog_id = c.catalog_id
GROUP BY c.catalog_id
ORDER BY average DESC, votes DESC;

使用DESC的SQL查询无法正常工作

2 个答案: