Select timestamps for these values SQL - sql

Question

Hello currently I have a working script below. I am using oracles 10
SELECT z.ID as "ID_One",
MAX(r.value) as "Max",
round(MAX(r.value)/80000,2) as "ROUND"
FROM Table1 r, Table2 z
WHERE r.timestamp > ((SYSDATE - TO_DATE('01/01/1970 00:00:00', 'MM-DD-YYYY HH24:MI:SS')) * 24 * 60 * 60) - 80000
AND r.id=21
AND r.animalid IN ('7','98','3','3')
AND r.id = z.id group by r.id, r.animalid,z.id;
It produces a table like this
ID_ONE MAX ROUND
1 500 232
2 232 32
3 23 .21
4 34 .321
I want to select a row call timestamp from table r. However when I add " r.timestamp " in to my query it produces 500 rows of data instead of 4. It looks like it is producing the the highest number for each timestamp instead. How would I produce a table that looks like this ? fyi timestamp column is in unix time. I can do the conversion myself. I just need to know how to get out these rows.
ID_ONE MAX ROUND TIMESTAMP
1 500 232 DEC 21,2021 10:00
2 232 32 DEC 21,2021 23:12
3 23 .21 DEC 31,2021 2:12
4 34 .321 DEC 31,2021 23:12

Answer 1

If you want other values from the row you're getting the MAX from, you can use analytic functions in a subquery instead of aggregates. There are various ways; this one ranks each row in the original tables such that the row with the highest value for each id is ranked first, and the outer query then only returns those.
SELECT id AS "ID_One",
value as "Max",
ROUND(value/80000,2) AS "ROUND",
timestamp,
TO_CHAR(DATE '1970-01-01' + (timestamp / (24 * 60 * 60)),
'MON DD,YYYY HH24:MI') AS timestamp_date
FROM (
SELECT z.id,
r.value,
r.timestamp,
RANK() OVER (PARTITION BY r.id, r.animalid ORDER BY r.value DESC) AS rnk
FROM Table1 r, Table2 z
WHERE r.timestamp > ((SYSDATE - DATE '1970-01-01') * 24 * 60 * 60) - 80000
--AND r.id=21
AND r.animalid IN ('7','98','3','3')
AND r.id = z.id
)
WHERE rnk = 1;
ID_One Max ROUND TIMESTAMP TIMESTAMP_DATE
---------- ---------- ---------- ---------- --------------------------
1 500 .01 1640080800 DEC 21,2021 10:00
2 232 0 1640128320 DEC 21,2021 23:12
3 23 0 1640916720 DEC 31,2021 02:12
4 34 0 1640992320 DEC 31,2021 23:12
SQL Fiddle, including the inner query on its own so you can see the ranking applied to each row.