mysql - 数据库的最新结果

Question

我需要仅显示最新项目的两个连接表的结果。我有以下疑问:

  SELECT project.id,
         project.created,
         COUNT(DISTINCT events.user_id) AS cnt
    FROM project
    JOIN events ON (events.project_id = project.id)
   WHERE project.creator = $creatorID
     AND events.user_id != $creatorID
ORDER BY project.created DESC
   LIMIT 1

出于某种原因，我不断获得第一个项目......我在这里错过了什么？

Answer 1

您绝对走在正确的道路上。您似乎缺少聚合 COUNT() 的 GROUP BY 子句。试试这个:

SELECT
  project.id,
  project.created,
  count(DISTINCT events.user_id) AS cnt
FROM project
  JOIN events ON (events.project_id = project.id)
WHERE
  project.creator = $creatorID
  AND events.user_id != $creatorID
GROUP BY project.id, project.created
ORDER BY project.created DESC,
LIMIT 1