Question

table(ms_replies)  
|------------------------------------------|
| id | ticketID |  replyStamp              |
|------------------------------------------|
| 1  |  7       | Tue 11 Oct 2011, 8:56am  |
| 2  |  7       | Wed 12 Oct 2011, 9:20am  |
| 3  |  8       | Wed 12 Oct 2011, 16:24pm |
| 4  |  7       | Thu 27 Oct 2011, 20:28pm |
| 5  |  8       | Tue 18 Oct 2011, 9:54am  |
|------------------------------------------|

The code I have thus far is:

SELECT 
    ticketID,
    MAX(replace(replace(replyStamp, 'pm',''), 'am','')) AS time
FROM 
    ms_replies 
WHERE 
    `ticketID` IN ($IDs)
GROUP BY 
    ticketID

But this doesn’t return the most recent entry.

Please note the replace in the query is necesary to remove the am | pm , this is not my doing, but I cannot chage it, unfortunatly.

Answer 1

You have to convert your strings into dates if you want to compare them as dates:

SELECT ticketID,
         MAX(STR_TO_DATE(
           REPLACE(REPLACE(replyStamp, 'am', ''), 'pm', ''), 
           '%a %d %b %Y, %T')) AS max_time
    FROM ms_replies 
   WHERE ticketID IN (7, 8)
GROUP BY ticketID;

But it’s actually not required if the latest entry always have the max id (as in your sample); then you can just check MAX(id) instead, like in @ZaneBien answer – or here:

SELECT m.ticketID, m.replyStamp
  FROM ms_replies AS m
 WHERE m.id = (
         SELECT MAX(id) FROM ms_replies 
         WHERE ticketID = m.ticketID
       );