MYSQL Select MAX Date inside a join statement
I'm trying to return a record number's historic locations
What I have is:
SELECT l.location, t.transaction_id, t.date_modified
FROM transactions as t
INNER JOIN (
SELECT
t1.received_id, t1.transaction_id, t1.date_modified
FROM (
SELECT received_id, MAX(date_modified) as maxmodify
FROM transactions
GROUP BY received_id) as max_record
JOIN transactions as t1
ON (t1.received_id =max_record.received_id)
) as whatever
INNER JOIN locations as l
ON l.location_id = t.location_id
INNER JOIN received as r
ON r.received_id = t.received_id
WHERE t.received_id='1782'
ORDER BY t.date_modified DESC
This takes about 1 min to parse and returns data like:
T-E1A 67294 2013-05-29 14:05:30
T-E1A 67293 2013-05-29 14:05:30
T-E1A 67294 2013-05-29 14:05:30
T-E1A 67293 2013-05-29 14:05:30
T-E1A 67294 2013-05-29 14:05:30
T-E1A 67293 2013-05-29 14:05:30
T-E1A 67294 2013-05-29 14:05:30
What I'm really expecting to see is data like from a query like this:
SELECT l.location, t.transaction_id, t.date_modified FROM transactions as t
JOIN locations as l
ON l.location_id = t.location_id
JOIN received as r
ON r.received_id = t.received_id
WHERE t.received_id='1782'
ORDER BY t.date_modified DESC
Which returns
T-E1A 67290 2013-05-29 13:58:26
T-E1A 67289 2013-05-29 13:58:26
ADJUST 67283 2013-04-26 11:33:54
ADJUST 67284 2013-04-26 11:33:54
ST10 67279 2013-04-26 09:52:41
ST10 67278 2013-04-26 09:52:13
ST10 67277 2013-04-26 09:50:58
ST10 67276 2013-04-26 09:50:20
SH3 67274 2013-04-26 09:49:39
This second query is better but I really want to only show the last modified time for each record id and location.
Can anybody see what I'm doing wrong? I appreciate the help.
Something like this...
SELECT t1.received_id
, t1.transaction_id
, t1.date_modified
, l.location
FROM transactions t1
JOIN ( SELECT received_id, MAX(date_modified) maxmodify FROM transactions GROUP BY received_id) max_record
ON max_record.received_id = t1.received_id
AND max_record.maxmodify = t1.date_modified
JOIN locations l
ON l.location_id = t1.location_id
JOIN received r
ON r.received_id = t1.received_id
WHERE t1.received_id = '1782'
ORDER
BY t1.date_modified DESC
the kernel of which is this...
SELECT x.*
FROM my_table x
JOIN (SELECT id,MAX(thing) max_thing FROM my_table GROUP BY id) y
ON y.id = x.id
AND y.max_thing = x.thing;