14-cards-issued-difference.sql

-- Your team at JPMorgan Chase is preparing to launch a new credit card, and to gain some insights, you're analyzing how many credit cards were issued each month.

-- Write a query that outputs the name of each credit card and the difference in the number of issued cards between the month with the highest issuance cards and the lowest issuance. Arrange the results based on the largest disparity.


-- Solution 1 (solved)
SELECT   card_name, MAX(issued_amount) - MIN(issued_amount) as difference
FROM     monthly_cards_issued
GROUP BY card_name
ORDER BY 2 DESC




-- my initial approach: 

SELECT DISTINCT(card_name) 
FROM monthly_cards_issued
WHERE issued_amount = (
  SELECT MAX(issued_amount) - MIN(issued_amount)
  FROM monthly_cards_issued)


-- remarks: complicated the problem initially, but found the solution after some time.