How can I select records from the last value accumulated - sql

Question

I have the next data: TABLE_A
RegisteredDate
Quantity
2022-03-01 13:00
100
2022-03-01 13:10
20
2022-03-01 13:20
-80
2022-03-01 13:30
-40
2022-03-02 09:00
10
2022-03-02 22:00
-5
2022-03-03 02:00
-5
2022-03-03 03:00
25
2022-03-03 03:20
-10
If I add cumulative column
select RegisteredDate, Quantity
, sum(Quantity) over ( order by RegisteredDate ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) as Summary
from TABLE_A
RegisteredDate
Quantity
Summary
2022-03-01 13:00
100
100
2022-03-01 13:10
20
120
2022-03-01 13:20
-80
40
2022-03-01 13:30
-40
0
2022-03-02 09:00
10
10
2022-03-02 22:00
-5
5
2022-03-03 02:00
-5
0
2022-03-03 03:00
25
25
2022-03-03 03:20
-10
15
Is there a way to get the following result with a query?
RegisteredDate
Quantity
Summary
2022-03-03 03:00
25
25
2022-03-03 03:20
-10
15
This result is the last records after the last zero.
EDIT:
Really for the solution to this problem I need the: 2022-03-03 03:00 is the first date of the last records after the last zero.

Answer 1

You can try to use SUM aggregate window function to calculation grp column which part represent to last value accumulated.
Query 1:
WITH cte AS
(
SELECT RegisteredDate,
Quantity,
sum(Quantity) over (order by RegisteredDate ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) as Summary
FROM TABLE_A
), cte2 AS (
SELECT *,
SUM(CASE WHEN Summary = 0 THEN 1 ELSE 0 END) OVER(order by RegisteredDate desc) grp
FROM cte
)
SELECT RegisteredDate,
Quantity
FROM cte2
WHERE grp = 0
ORDER BY RegisteredDate
Results:
| RegisteredDate | Quantity |
|----------------------|----------|
| 2022-03-03T03:00:00Z | 25 |
| 2022-03-03T03:20:00Z | -10 |

Answer 2

Use a CTE that returns the summary column and NOT EXISTS to filter out the rows that you don't need:
WITH cte AS (SELECT *, SUM(Quantity) OVER (ORDER BY RegisteredDate) Summary FROM TABLE_A)
SELECT c1.*
FROM cte c1
WHERE NOT EXISTS (
SELECT 1
FROM cte c2 WHERE c2.RegisteredDate >= c1.RegisteredDate AND c2.Summary = 0
)
ORDER BY c1.RegisteredDate;
There is no need for ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW in the OVER clause of the window function, because this is the default behavior.
See the demo.

Answer 3

Try this:
with u as
(select RegisteredDate,
Quantity,
sum(Quantity) over (order by RegisteredDate ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) as Summary
from TABLE_A)
select * from u
where RegisteredDate >= all(select RegisteredDate from u where Summary = 0)
and Summary <> 0;
Fiddle
Basically what you want is for RegisteredDate to be >= all RegisteredDatess where Summary = 0, and you want Summary <> 0.

Answer 4

When using window functions, it is necessary to take into account that RegisteredDate column is not unique in TABLE_A, so ordering only by RegisteredDate column is not enough to get a stable result on the same dataset.
With A As (
Select ROW_NUMBER() Over (Order by RegisteredDate, Quantity) As ID, RegisteredDate, Quantity
From TABLE_A),
B As (
Select A.*, SUM(Quantity) Over (Order by ID) As Summary
From A)
Select Top 1 *
From B
Where ID > (Select MAX(ID) From B Where Summary=0)
ID
RegisteredDate
Quantity
Summary
8
2022-03-03 03:00
25
25