Topic
Aggregation
GROUP BY, HAVING and conditional aggregates. The recurring skill is filtering at the right stage — WHERE before grouping, HAVING after — and knowing why COUNT(*) and COUNT(column) disagree.
New to this? Read the Aggregate functions: SUM, AVG, COUNT, MIN, MAX chapter.
easyAverage balance by account typeGXBank · aggregationBasic→easyCompleted rides by cityGrab · aggregationFree→easyOrders by statusShopee · aggregationFree→mediumAd click-through conversion rate, per campaignGrab · aggregationBasic→mediumDefect rate per production lineIntel · aggregationBasic→mediumPivot quarterly sales into columnsGoTo · aggregationBasic→mediumSplit mudarabah profit across depositors by weighted balanceBank Islam · aggregationFree→mediumTop 3 restaurants by ordersFoodpanda · aggregationBasic→mediumUtilisation rate per consultantDeloitte · aggregationFree→hardPivot payment channels into columns, per merchantGCash · aggregationBasic→