Group by day from timestamp

Question

In my posts table, it saves timestamp for each post record.

What query can group posts by day, using this timestamp column?

Answer 1

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

This found for me. I have timestamp like "2013-03-27 15:46:08".

Answer 2

How about this? Using the DATE function:

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

This will show you the number of posts on each date that the table has data for.

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