How can I get cumulative sum using SQL? - sql

Question

I have a table of individual sales, for which I would like to summarize into two columns, with a monthly total in one and a cumulative sum in another.
Company A and Company B are subsidiary company under the same parent company, thus, need to be considered as one for calculating cumulative income.
I tried this code and output is following:
SUM(INCOME) OVER(PARTITION BY COMPANY ORDER BY MONTH ROWS UNBOUNDED PRECEDING) AS CUMULATIVE
Company Month Income Cumulative
Company A 1 20 20
Company B 1 0 20
Company C 1 20 20
Company A 2 20 40
Company B 2 0 40
But I want to return 0 when Company B has 0 income for cumulative
Company Month Income Cumulative
Company A 1 20 20
Company B 1 0 0
Company C 1 20 20
Company A 2 20 40
Company B 2 0 0
How can I return 0 for cumulative when either company A or company B has income of 0?!

Answer 1

You have a bad design for the prupose you want and need
adding an identidy field for sorting purposes and converting your short name into numbers, you can achieve it with window function.
A column for the year is also necessary as you can't sort when you got two janissary for the same company
CREATE TABLE tabl1 (
id_num int IDENTITY(1,1),
Company VARCHAR(9),
Month VARCHAR(3),
Income INTEGER
);
INSERT INTO tabl1
(Company, Month, Income)
VALUES
('Company A', 'Jan', '20'),
('Company B', 'Jan', '0'),
('Company A', 'Feb', '20'),
('Company B', 'Feb', '0'),
('Company C', 'Jan', '20');
5 rows affected
SELECT
Company, Month, Income,
SUM(Income) OVER(PARTITION BY company ORDER BY
CASE WHEN Month= 'Jan' THEN 1
WHEN Month = 'Feb' THEN 2
WHEN Month = 'Dec' THEN 12
END) as Cumulative
FROM
tabl1
ORDER BY id_num
Company
Month
Income
Cumulative
Company A
Jan
20
20
Company B
Jan
0
0
Company A
Feb
20
40
Company B
Feb
0
0
Company C
Jan
20
20
fiddle
So a better would be
CREATE TABLE tabl1 (
id_num int IDENTITY(1,1),
Company VARCHAR(9),
Month VARCHAR(3),
[Year] int,
Income INTEGER
);
INSERT INTO tabl1
(Company, Month,[Year], Income)
VALUES
('Company A', 'Jan',2023, '20'),
('Company B', 'Jan',2023, '0'),
('Company A', 'Feb',2023, '20'),
('Company B', 'Feb',2023, '0'),
('Company C', 'Jan',2023, '20');
5 rows affected
SELECT
Company, Month,[Year], Income,
SUM(Income) OVER(PARTITION BY company ORDER BY
CASE WHEN Month= 'Jan' THEN 1
WHEN Month = 'Feb' THEN 2
WHEN Month = 'Dec' THEN 12
END, YEAR ) as Cumulative
FROM
tabl1
ORDER BY id_num
Company
Month
Year
Income
Cumulative
Company A
Jan
2023
20
20
Company B
Jan
2023
0
0
Company A
Feb
2023
20
40
Company B
Feb
2023
0
0
Company C
Jan
2023
20
20
fiddle