Tricky~25min
The Promotion Paradox
Promo A is profitable. Promo B is profitable. Both are running simultaneously. CFO says margins are collapsing. Marketing says both promos are fine. Someone is right.
Tables you'll query
orderspromo_applicationsorder_itemspromotions
What you'll learn
UNION / INTERSECT / EXCEPTJOINsAggregations & GROUP BY