SQL retrieving 1st run data from a date range - c++

Question

I need to retrieve 1st run information from an Oracle database for a particular date range. First run means ignoring rows where serial numbers that are run at a later time.
Note: 1 = Passed, 0 = Fail
Example of my data is:
SERIALNUM TIMESTAMP_ PASSED …{more data}
001 2015-01-07T11:22:50 0
002 2015-01-07T11:24:00 0
003 2015-01-07T11:25:50 1
001 2015-01-07T11:26:50 1
004 2015-01-07T11:28:50 1
005 2015-01-07T11:29:50 1
006 2015-01-07T11:31:50 1
002 2015-01-07T11:30:50 0
002 2015-01-07T11:33:50 1
007 2015-01-07T11:35:50 1
008 2015-01-07T11:36:50 1
0010 2015-01-07T11:39:50 1
009 2015-01-07T11:37:50 1
Desired results, 10 units tested, 2 failed, 8 passed.
Using Excel to get my proper 1st run data I:
[step1] Delete rows outside of my date range.
[step2] Sort by SERIALNUM (1st level) TIMESTAMP_ (2nd level).
[step3] Remove Duplicate SERIALNUM.
[step4] Then count the number of passed units (1 = pass).
This gives me my desired results.
Changing the order gives me undesired results.
I can get the data from the database from my selected range by using:
SELECT SERIALNUM, TIMESTAMP_, PASSED
FROM dbTble
WHERE TO_DATE('01/07/2015 09:00:00', 'MM/DD/YYYY HH24:MI:SS') <= TIMESTAMP_
AND TIMESTAMP_ < TO_DATE('01/07/2015 14:59:59', 'MM/DD/YYYY HH24:MI:SS')
ORDER BY SERIALNUM, TIMESTAMP_
It seems like I should be using subquery, but I saw a note that subquery cannot be sorted.
How can I accomplish this with SQL command?

Answer 1

This will get the first run (only) of runs within the date range. If there is a run for a particular serialnum earlier than the minimum date of the range, it won't be excluded:
SELECT serialnum, timestamp_, passed FROM (
SELECT serialnum, timestamp_, passed
, ROW_NUMBER() OVER ( PARTITION BY serialnum ORDER BY timestamp_ ) AS rn
FROM dbtable
WHERE TO_DATE('01/07/2015 09:00:00', 'MM/DD/YYYY HH24:MI:SS') <= timestamp_
AND timestamp_ < TO_DATE('01/07/2015 14:59:59', 'MM/DD/YYYY HH24:MI:SS')
) WHERE rn = 1
ORDER BY serialnum, timestamp_
The window function ROW_NUMBER() ranks according to earliest (use DESC after timestamp_ to force latest).
Hope this helps.