how to get mysql ranking among results with same id
Quick question, I have a table of messages each with a timestamp and a reply_id and a topic_id. Reply_ids can be the same as others, which means those messages are in the same group of replies. When I select a reply_id with the min timestamp, meaning it was the first message of that group, I would also like to know its numbered place within all results o开发者_高级运维f that topic_id, ex. 3rd (3) 4th(4) etc. Anyone know how to do this or have any suggestions? Can this be done in pure sql?
SELECT reply_id,min(timestamp) as min FROM messages
WHERE reply_chunk_id = ?
AND topic_id = ?
Using pure SQL:
SELECT m.reply_id,
MIN(m.timestamp) as min,
(SELECT COUNT(*)
FROM MESSAGES t
WHERE t.id <= m.id) AS rank
FROM MESSAGES m
WHERE m.reply_chunk_id = ?
AND m.topic_id = ?
This works only if replyid
is unique values. If there's a duplicate replyid
before the replyid
, then the COUNT will miss that.
Analytic functions, which MySQL doesn't support, would be a better option. You can recreate the functionality using variables in the MySQL SELECT statements.
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