the-number-of-users-that-are-eligible-for-discount.sql

# Time:  O(n)
# Space: O(n)

CREATE FUNCTION getUserIDs(startDate DATE, endDate DATE, minAmount INT) RETURNS INT
BEGIN
  RETURN (
    SELECT COUNT(DISTINCT user_id) AS user_cnt
    FROM Purchases
    WHERE time_stamp >= startDate AND time_stamp <= endDate AND amount >= minAmount
  );
END