Calculate balance amount in redshift - sql

Question

DB-Fiddle
CREATE TABLE inventory (
id SERIAL PRIMARY KEY,
stock_date DATE,
inbound_quantity INT,
outbound_quantity INT
);
INSERT INTO inventory
(stock_date, inbound_quantity, outbound_quantity
)
VALUES
('2020-01-01', '900', '0'),
('2020-01-02', '0', '300'),
('2020-01-03', '400', '250'),
('2020-01-04', '0', '100'),
('2020-01-05', '700', '500');
Expected Output:
stock_date
inbound_quantity
outbound_quantity
balance
2020-01-01
900
0
900
2020-01-02
0
300
600
2020-01-03
400
250
750
2020-01-04
0
100
650
2020-01-05
700
500
850
Query:
SELECT
iv.stock_date AS stock_date,
iv.inbound_quantity AS inbound_quantity,
iv.outbound_quantity AS outbound_quantity,
SUM(iv.inbound_quantity - iv.outbound_quantity) OVER (ORDER BY stock_date ASC) AS Balance
FROM inventory iv
GROUP BY 1,2,3
ORDER BY 1;
With the above query I am able to calculate the balance of inbound_quantity and outbound_quantity in PostgresSQL.
However, when I run the same query in Amazon-Redshift I get this error:
Amazon Invalid operation: Aggregate window functions with an ORDER BY clause require a frame clause;
1 statement failed.
How do I need to change the query to also make it work in Redshift?

Answer 1

As the error speaks, you need to add the frame specification clause, namely the ROWS UNBOUNDED PRECEDING into your window function.
SELECT iv.stock_date AS stock_date,
iv.inbound_quantity AS inbound_quantity,
iv.outbound_quantity AS outbound_quantity,
SUM(iv.inbound_quantity - iv.outbound_quantity) OVER (
ORDER BY stock_date ASC
ROWS UNBOUNDED PRECEDING
) AS Balance
FROM inventory iv
GROUP BY 1,2,3
ORDER BY 1;