Oracle SQL Group By a String Aggregated Field - sql

Question

I'm having a problem grouping a field in my query. Here is an example of what I'm talking about:
Example:
AIR_DT DOL_GAP_TIME MATL_SIZE
15-JAN-15 8:00 AM 30
15-JAN-15 8:00 AM 25
15-JAN-15 9:00 AM 5
15-JAN-15 9:00 AM 10
15-JAN-15 9:00 AM 5
15-JAN-15 9:00 AM 20
Those with same time should be grouped as one, summing up their matl_size
Expected output:
AIR_DT DOL_GAP_TIME MATL_SIZE
15-JAN-15 8:00 AM 55
15-JAN-15 9:00 AM 40
Here is my SQL:
SELECT
a.air_dt,
TRIM(SUBSTR(TO_CHAR (a.dol_pref_start_time, 'mm/dd/yyyy hh:mi:ss AM'),12,2))
|| ':00 '
|| TRIM(SUBSTR (TO_CHAR (a.dol_pref_start_time, 'mm/dd/yyyy hh:mi:ss AM'),
21, 2)) dol_gap_time, e.matl_size
FROM order_implem_dtl_broadcast a, matl_mstr b, matl_size_mstr e
WHERE a.matl_id = b.matl_id
AND b.matl_size_id = e.matl_size_id
AND a.air_dt LIKE '%15-JAN-15%'
GROUP BY a.air_dt, a.dol_pref_start_time, e.matl_size
ORDER BY a.air_dt, a.dol_pref_start_time;
Thank you for helping in advance!

Answer 1

Based on your sample data, this should do what you want:
select AIR_DT, DOL_GAP_TIME, sum(MATL_SIZE)
from table t
group by AIR_DT, DOL_GAP_TIME;
However, I have no idea what this has to do with the query in the question.

Answer 2

OK let's start with your initial query:
SELECT
a.air_dt,
TRIM(SUBSTR(TO_CHAR (a.dol_pref_start_time, 'mm/dd/yyyy hh:mi:ss AM'),12,2))
|| ':00 '
|| TRIM(SUBSTR (TO_CHAR (a.dol_pref_start_time, 'mm/dd/yyyy hh:mi:ss AM'), 21, 2)) dol_gap_time, e.matl_size
FROM order_implem_dtl_broadcast a, matl_mstr b, matl_size_mstr e
WHERE a.matl_id = b.matl_id
AND b.matl_size_id = e.matl_size_id
AND a.air_dt LIKE '%15-JAN-15%'
GROUP BY a.air_dt, a.dol_pref_start_time, e.matl_size
ORDER BY a.air_dt, a.dol_pref_start_time;
I see a couple of problems. One, you're grouping by e.matl_size even though that is the column you want to SUM(). You don't want it in the GROUP BY. Second, your manner of getting the time from dol_pref_start_time is really odd. It looks like you want to round down to the hour, then just get the hour plus whether it is AM or PM. So this:
TRIM(SUBSTR(TO_CHAR (a.dol_pref_start_time, 'mm/dd/yyyy hh:mi:ss AM'),12,2))
|| ':00 '
|| TRIM(SUBSTR (TO_CHAR (a.dol_pref_start_time, 'mm/dd/yyyy hh:mi:ss AM'), 21, 2)) dol_gap_time
can simply be this:
TO_CHAR(TRUNC(a.dol_pref_start_time, 'HH'), 'HH:MI AM') AS dol_gap_time
Third, are your dates stored as dates? If so, why are you doing this?
AND a.air_dt LIKE '%15-JAN-15%'
It would be far better to do this:
AND TRUNC(a.air_dt) = date'2015-01-15'
or, if you have an index on a.air_dt, this:
AND a.air_dt >= date'2015-01-15'
AND a.air_dt < date'2015-01-16'
Putting this all together, we get something like this (note that I've also converted your joins to ANSI SQL joins):
SELECT TRUNC(a.air_dt) AS air_dt
, TO_CHAR(TRUNC(a.dol_pref_start_time, 'HH'), 'HH:MI AM') AS dol_gap_time
, SUM(e.matl_size) AS matl_size
FROM order_implem_dtl_broadcast a INNER JOIN matl_mstr b
ON a.matl_id = b.matl_id
INNER JOIN matl_size_mstr e
ON b.matl_size_id = e.matl_size_id
WHERE a.air_dt >= date'2015-01-15'
AND a.air_dt < date'2015-01-16'
GROUP BY TRUNC(a.air_dt), TO_CHAR(TRUNC(a.dol_pref_start_time, 'HH'), 'HH:MI AM')
ORDER BY air_dt, TO_DATE(dol_gap_time, 'HH:MI AM'); -- using aliases in the ORDER BY, converting dol_gap_time to DATE for sorting