SQL GROUP BY WITH CONDITIONAL SUM (CASE WHEN)

example_table.sql

CREATE TABLE test (
  id INT PRIMARY KEY AUTO_INCREMENT,
  year SMALLINT,
  month TINYINT,
  day TINYINT,
  revenue INT
);

INSERT INTO test (year, month, day, revenue) VALUES 
(2020, 01, 31, 9000),
(2020, 02, 29, 1500),
(2020, 02, 30, 2000),
(2020, 02, 31, -7500),
(2020, 03, 30, 2000),
(2020, 03, 31, 1700),

(2021, 01, 31, 1000),
(2021, 02, 31, 1200),
(2021, 03, 31, 1900),

(2022, 01, 31, 1000),
(2022, 02, 31, 1540),
(2021, 03, 31, 1980);

expected_result.csv

group_by_year_and_sum_by_condition_case_when.sql

SELECT year, SUM(CASE WHEN month = 02 THEN revenue ELSE 0 END) as feb
FROM test
GROUP BY year;