mysql - Mysql - 获取每个家庭的最新历史记录

Question

我需要为数据库中的每个家庭获取最新的历史项目（来自某个类别 - 1422）。我看到了几个例子，并来到了这个查询：

SELECT *, MAX(created_at) 
FROM family_histories
WHERE family_history_cat_id = 1422
GROUP BY family_id

好吗？

Answer 1

您也可以使用 INNER JOIN 获取每个组的 MAX id

SELECT
  fh.*
FROM family_histories
  INNER JOIN (SELECT
        family_history_cat_id,
        MAX(created_at)
          FROM family_histories
          GROUP BY family_id) AS l
    ON l.family_history_cat_id = fh.family_history_cat_id
WHERE fh.family_history_cat_id = 1422

Answer 2

尝试

SELECT *
FROM family_histories
WHERE family_history_cat_id = 1422
GROUP BY family_id
ORDER BY created_at DESC
LIMIT 1