Oracle - select rows with minimal value in a subset - sql

Question

I have a following table of dates:
dateID INT (PK),
personID INT (FK),
date DATE,
starttime VARCHAR, --Always in a format of 'HH:MM'
What I want to do is I want to pull rows (all columns, including PK) with lowest date (primary condition) and starttime (secondary condition) for every person. For example, if we have
row1(date = '2013-04-01' and starttime = '14:00')
and
row2(date = '2013-04-02' and starttime = '08:00')
row1 will be retrieved, along with all other columns.
So far I have come up with gradual filtering the table, but it`s quite a mess. Is there more efficient way of doing this?
Here is what I made so far:
SELECT
D.id
, D.personid
, D.date
, D.starttime
FROM table D
JOIN (
SELECT --Select lowest time from the subset of lowest dates
A.personid,
B.startdate,
MIN(A.starttime) AS starttime
FROM table A
JOIN (
SELECT --Select lowest date for every person to exclude them from outer table
personid
, MIN(date) AS startdate
FROM table
GROUP BY personid
) B
ON A.personid = B.peronid
AND A.date = B.startdate
GROUP BY
A.personid,
B.startdate
) C
ON C.personid = D.personid
AND C.startdate = D.date
AND C.starttime = D.starttime
It works, but I think there is a more clean/efficient way to do this. Any ideas?
EDIT: Let me expand a question - I also need to extract maximum date (only date, without time) for each person.
The result should look like this:
id
personid
max(date) for each person
min(date) for each person
min(starttime) for min(date) for each person
It is a part of a much larger query (the resulting table is joined with it), and the resulting table must be lightweight enough so that the query won`t execute for too long. With single join with this table (just using min, max for each field I wanted) the query took about 3 seconds, and I would like the resulting query not to take longer than 2-3 times that.

Answer 1

you should be able to do this like:
select a.dateID, a.personID, a.date, a.max_date, a.starttime
from (select t.*,
max(t.date) over (partition by t.personID) max_date,
row_number() over (partition by t.personID
order by t.date, t.starttime) rn
from table t) a
where a.rn = 1;
sample data added to fiddle: http://sqlfiddle.com/#!4/63c45/1

Answer 2

This is the query you can use and no need to incorporate in your query. You can also use #Dazzal's query as stand alone
SELECT ID, PERSONID, DATE, STARTTIME
(
SELECT ID, PERONID, DATE, STARTTIME, ROW_NUMBER() OVER(PARTITION BY personid ORDER BY STARTTIME, DATE) AS RN
FROM TABLE
) A
WHERE
RN = 1

Answer 3

select a.id,a.accomp, a.accomp_name, a.start_year,a.end_year, a.company
from (select t.*,
min(t.start_year) over (partition by t.company) min_date,
max(t.end_year) over (partition by t.company) max_date,
row_number() over (partition by t.company
order by t.end_year desc) rn
from temp_123 t) a
where a.rn = 1;