Problem
Monthly Transactions I - LeetCode
Monthly Transactions I - Level up your coding skills and quickly land a job. This is the best place to expand your knowledge and get prepared for your next interview.

Solution
SELECT
DATE_FORMAT(trans_date, "%Y-%m") AS month,
country,
COUNT(id) AS trans_count,
SUM(state = 'approved') AS approved_count,
SUM(amount) AS trans_total_amount,
SUM(CASE
WHEN state = 'approved' THEN amount
ELSE 0
END) AS approved_total_amount
FROM Transactions
GROUP BY month, country