Tricky~22min
The Coupon Cascade
Finance spots ~₹4.18L in unplanned coupon discounts from code BETA30. It was issued to 12 beta testers. The redemption log shows 430 uses. Something is very wrong.
Tables you'll query
couponscoupon_issuancesredemptions
What you'll learn
SubqueriesJOINsAggregations & GROUP BY