Question

在我的posts表格中，它会为每个帖子记录保存时间戳。

使用此时间戳列，哪些查询可以按天分组？

Answer 1

这个怎么样？使用DATE函数：

 SELECT DATE(FROM_UNIXTIME(MyTimestamp)) AS ForDate,
        COUNT(*) AS NumPosts
 FROM   MyPostsTable
 GROUP BY DATE(FROM_UNIXTIME(MyTimestamp))
 ORDER BY ForDate

这将显示表格包含数据的每个日期的帖子数量。

Answer 2

SELECT DATE(timestamp) AS ForDate,
        COUNT(*) AS NumPosts
 FROM   user_messages
 GROUP BY DATE(timestamp)
 ORDER BY ForDate

这为我找到了。我有时间戳，如“2013-03-27 15:46:08”。

Answer 3

SELECT
    *
FROM
(
    SELECT DATE(FROM_UNIXTIME(MyTimestamp)) AS ForDate,
           ROW_NUMBER() OVER (PARTITION BY DATE(FROM_UNIXTIME(MyTimestamp)) ORDER BY MyTimeStamp) AS PostRowID,
           *
    FROM   MyPostsTable
)
    AS sequenced_daily_posts
WHERE
    ForDate = <whatever date(s) you want>
    AND PostRowID <= 2

从时间戳开始按天分组

3 个答案: