ORACLE: Select row, if most recent value of column equals X - oracle

Question

I'll preemptively say I search the other questions and online, however could not find it. Whether that be poor wording choice on my part, or otherwise.
I have a ticketing queue and searching through it's history. Column "Group" will contain the group name that owns the ticket upon a transfer action. There are many other actions, such as just adding comments to the ticket. I am only interested if the most recent value in the column (ignoring nulls) if it is "QUEUE_X".
I know this is improper because of the group-function but this is logically how I view it:
select
*
from
ticket_history
where
max(group) = 'QUEUE_X'
order by
date
;
I don't want to strictly do where group = 'X' because tickets can be transferred around a lot and I only care about the tickets in my queue at the current time. Also, I cannot find if or where the original developer put a CURRENT_QUEUE-like column, so out of luck the easy way. Don't take it too literal, just wanted to illustrate the null values in GROUP and I'd like the most recent value to equal Queue_X
Example table data of a ticket I would NOT want (though if the query occured at 12:12, I would have):
STRT_DATE | PERSON | GROUP | TICKET_NUM | END_DATE
12/3/15 12:00 | Ted | Queue_Y | 111111 | 12/3/15 12:05
12/3/15 12:05 | Bob | | 111111 | 12/3/15 12:10
12/3/15 12:10 | Ted | Queue_Y | 222222 | 12/3/15 12:45
12/3/15 12:10 | Bob | Queue_X | 111111 | 12/3/15 12:15
12/3/15 12:15 | Bob | | 222222 | 12/3/15 12:45
12/3/15 12:15 | Mary | Queue_Y | 111111 | 12/3/15 12:25
12/3/15 12:25 | Ted | | 222222 | 12/3/15 12:35
12/3/15 12:35 | Ted | | 333333 | 12/3/15 12:45
12/3/15 12:35 | Bob | Queue_X | 333333 | 12/3/15 12:45
12/3/15 12:45 | Ted | | 111111 | 12/3/15 12:55
12/3/15 12:55 | Bob | Queue_X | 111111 | 12/3/15 12:56
Desired Results:
12/3/15 12:35 | Bob | Queue_X | 333333 | 12/3/15 12:45
12/3/15 12:55 | Bob | Queue_X | 111111 | 12/3/15 12:56
(Still in Queue_Y):
12/3/15 12:10 | Ted | Queue_Y | 222222 | 12/3/15 12:45
Thank you in advance.
EDIT: Added more tickets and an additional member to Queue_Y (so there is not a 1-1 relationship between queue and person)

Answer 1

not totally sure what you are trying to accomplish but I think you want something like dense_rank() here is one I put together mytable represents your data, t1 does the dense rank check
ok here is the query running after 12:15 and no data is returned.
WITH mytable
AS (SELECT TO_DATE ('12/3/15 12:00', 'mm/dd/yy hh:mi') AS strt_dt,
'Ted' AS person,
'Queue_Y' AS grp,
123456 AS ticket_num
FROM DUAL
UNION ALL
SELECT TO_DATE ('12/3/15 12:05', 'mm/dd/yy hh:mi') AS strt_dt,
'Bob',
NULL,
123456
FROM DUAL
UNION ALL
SELECT TO_DATE ('12/3/15 12:10', 'mm/dd/yy hh:mi') AS strt_dt,
'Bob',
'Queue_X',
123456
FROM DUAL
UNION ALL
SELECT TO_DATE ('12/3/15 12:15', 'mm/dd/yy hh:mi') AS strt_dt,
'Ted',
'Queue_Y',
123456
FROM DUAL),
t2
AS (SELECT mytable.*,
DENSE_RANK ()
OVER (PARTITION BY ticket_num ORDER BY strt_dt DESC)
AS test_for_Q
FROM mytable)
SELECT strt_dt, person, grp, ticket_num
FROM t2
WHERE ticket_num IN (SELECT ticket_num
FROM t2
WHERE test_for_Q = 1 AND Grp = 'Queue_X')
now here is the query running at 12:12 and you get data back.
WITH mytable
AS (SELECT TO_DATE ('12/3/15 12:00', 'mm/dd/yy hh:mi') AS strt_dt,
'Ted' AS person,
'Queue_Y' AS grp,
123456 AS ticket_num
FROM DUAL
UNION ALL
SELECT TO_DATE ('12/3/15 12:05', 'mm/dd/yy hh:mi') AS strt_dt,
'Bob',
NULL,
123456
FROM DUAL
UNION ALL
SELECT TO_DATE ('12/3/15 12:10', 'mm/dd/yy hh:mi') AS strt_dt,
'Bob',
'Queue_X',
123456
FROM DUAL
-- UNION ALL
-- SELECT TO_DATE ('12/3/15 12:15', 'mm/dd/yy hh:mi') AS strt_dt,
-- 'Ted',
-- 'Queue_Y',
-- 123456
-- FROM DUAL
) ,
t2
AS (SELECT mytable.*,
DENSE_RANK ()
OVER (PARTITION BY ticket_num ORDER BY strt_dt DESC)
AS test_for_Q
FROM mytable)
SELECT strt_dt, person, grp, ticket_num
FROM t2
WHERE ticket_num IN (SELECT ticket_num
FROM t2
WHERE test_for_Q = 1 AND Grp = 'Queue_X')
results
STRT_DT,PERSON,GRP,TICKET_NUM
12/3/2015 12:10:00 PM,Bob,Queue_X,123456
12/3/2015 12:05:00 PM,Bob,,123456
12/3/2015 12:00:00 PM,Ted,Queue_Y,123456

Answer 2

If I understand your problem right your query would be:
select a.*
from ticket_history a
INNER JOIN ( select PERSON, GROUP, max(STRT_DATE) as maxdt
from ticket_history
where group = 'Queue_X'
group by PERSON, GROUP ) b
ON ( a.person = b.person
and a.group = b.group
and a.STRT_DATE = b.maxdt )
order by a.STRT_DATE desc
Please see if it is what you need, otherwise let me know.

Answer 3

Try this (edited):
select strt_date, person, group, ticket_num, end_date
from ticket_history
where (rowid, end_date) IN (select rowid, max(end_date)
from ticket_history
where group = 'QUEUE_X'
group by rowid)
order by end_date;
This will reflect what you show in your desired output.