Oracle query to keep looking until value is not 0 anymore - oracle

Question

I am using Oracle 11.
I have 2 tables
TblA with columns id, entity_id and effective_date.
TblADetail with columns id and value.
If Value = 0 for the effective date, I want to keep looking for the next effective date until I found value <> 0 anymore.
The below query only look for value on 3/10/21.
If value = 0, I want to look for value on 3/11/21. If that's not 0, I want to stop.
But, if that's 0, I want to look for value on 3/12/21. If that's not 0, I want to stop.
But, if that's 0, I want to keep looking until value is not 0.
How can I do that ?
SELECT SUM(pd.VALUE)
FROM TblA p,TblADetail pd
WHERE p.id = pd.id
AND p.effective_date = to_date('03/10/2021','MM/DD/YYYY')
AND TRIM (p.entity_id) = 123
Sample data:
TblA
id entity_id effective_date
1 123 3/10/21
2 123 3/11/21
3 123 3/12/21
TblADetail
id value
1 -136
1 136
2 2000
3 3000
In the above data, for entity_id 123, starting from effective_date 3/10/21, I would like to to return value 2000 (from TblADetail) effective_date 3/11/21.
So, starting from a certain date, I want the results from the minimum date that has non-zero values.
Thank you.

Answer 1

You can do what you need to do by grouping the sum on the effective date, and using the MIN analytic function to find the earliest date. Once you've done that, you simply need to select the date that matches the earliest date.
E.g.:
with tbla as (select 1 id, ' 123' entity_id, to_date('10/03/2021', 'dd/mm/yyyy') effective_date from dual union all
select 2 id, ' 123' entity_id, to_date('11/03/2021', 'dd/mm/yyyy') effective_date from dual union all
select 3 id, ' 123' entity_id, to_date('12/03/2021', 'dd/mm/yyyy') effective_date from dual),
tbla_detail as (select 1 id, -136 value from dual union all
select 1 id, 136 value from dual union all
select 2 id, 2000 value from dual union all
select 3 id, 3000 value from dual),
results as (select a.effective_date,
sum(ad.value) sum_value,
min(case when sum(ad.value) != 0 then a.effective_date end) over () min_effective_date
from tbla a
inner join tbla_detail ad on a.id = ad.id
where a.effective_date >= to_date('10/03/2021', 'dd/mm/yyyy')
and trim(a.entity_id) = '123'
group by a.effective_date)
select sum_value
from results
where effective_date = min_effective_date;
SUM_VALUE
----------
2000

Answer 2

Straightforward; read comments within code. Sample data in lines #1 - 13, query begins at line #14.
SQL> with
2 -- sample data
3 tbla (id, entity_id, effective_date) as
4 (select 1, 123, date '2021-03-10' from dual union all
5 select 2, 123, date '2021-03-11' from dual union all
6 select 3, 123, date '2021-03-12' from dual
7 ),
8 tblb (id, value) as
9 (select 1, -136 from dual union all
10 select 1, 136 from dual union all
11 select 2, 2000 from dual union all
12 select 3, 3000 from dual
13 ),
14 tblb_temp as
15 -- simple grouping per ID
16 (select id, sum(value) value
17 from tblb
18 group by id
19 )
20 -- return TBLA values whose ID equals TBLB_TEMP's minimum ID
21 -- whose value isn't zero
22 select a.id, a.entity_id, a.effective_date
23 from tbla a
24 where a.id = (select min(b.id)
25 from tblb_temp b
26 where b.value > 0
27 );
ID ENTITY_ID EFFECTIVE_
---------- ---------- ----------
2 123 03/11/2021
SQL>