MySQL ORDER BY，每种情况基于不同字段的CASE

Question

The query below works great. It orders results in two tiers, both based on s.points .

• Tier 1: All results with s.datesubmitted within the last hour.
• Tier 2: All results with s.datesubmitted previous to 1 hour ago.

The results in tier 1 take precedence over tier 2. So anything submitted within the last hour will display above anything submitted over an hour ago regardless of s.points .

The results in Tier 2 are all items submitted over 1 hour ago. Like Tier 1, they are ordered by s.points . How could I leave Tier 1 ordered by s.points , but make tier 2 ordered by most_recent ?

Thanks in advance,

John

   $sqlStr = "SELECT s.loginid, s.title, s.url, s.displayurl, s.points, s.datesubmitted, l.username,
               s.submissionid, s.subcheck, s.topten, COUNT(c.commentid) countComments, 
               GREATEST(s.datesubmitted, COALESCE(MAX(c.datecommented), s.datesubmitted)) AS most_recent
          FROM submission s
          JOIN login l ON s.loginid = l.loginid
     LEFT JOIN comment c ON s.submissionid = c.submissionid
      GROUP BY s.submissionid
      ORDER BY 
        CASE 
                 WHEN s.datesubmitted > DATE_SUB(NOW(), INTERVAL 1 HOUR) THEN 0 
                 WHEN s.datesubmitted > DATE_SUB(NOW(), INTERVAL 1 HOUR) THEN 1
                 ELSE 2 
               END, s.points DESC

         LIMIT $offset, $rowsperpage";

Answer 1

ORDER BY CASE 
             WHEN s.datesubmitted >= DATE_SUB(NOW(), INTERVAL 1 HOUR) THEN CONCAT(1, ',', s.points)
             WHEN s.datesubmitted < DATE_SUB(NOW(), INTERVAL 1 HOUR) THEN CONCAT(0, ',', s.datesubmitted)
         END DESC

In this case:

• Tier 1: All records within an hour will be sorted by points DESC
• Tier 2: All other records are sorted by datesubmitted DESC (most recent)

Answer 2

SELECT
  loginid, title, url, displayurl, points, datesubmitted, username,
  submissionid, subcheck, s.topten, countComments, most_recent
FROM (
  SELECT
    s.loginid, s.title, s.url, s.displayurl, s.points, s.datesubmitted, l.username,
    s.submissionid, s.subcheck, s.topten, COUNT(c.commentid) countComments, 
    GREATEST(s.datesubmitted, COALESCE(MAX(c.datecommented), s.datesubmitted)) AS most_recent,
    s.datesubmitted > DATE_SUB(NOW(), INTERVAL 1 HOUR) AS is_within_hour
  FROM submission s
    INNER JOIN login l ON s.loginid = l.loginid
    LEFT JOIN comment c ON s.submissionid = c.submissionid
  GROUP BY s.submissionid
) x
ORDER BY
  is_within_hour DESC,
  CASE WHEN     is_within_hour THEN points        END DESC,
  CASE WHEN NOT is_within_hour THEN datesubmitted END DESC
LIMIT $offset, $rowsperpage