mahir_data

The question bank

SQL Questions

55questions themed around companies you'll actually interview at in the region. Solve them right here: real Postgres, in your browser.

easyApplicants with no referral code on fileFree→easyAverage balance by account typeFree→easyCheapest flights to a destinationFree→easyClassify e-wallet balances into tiersFree→easyClassify insurance policies into tiersFree→easyClean up messy product namesFree→easyCompleted rides by cityFree→easyDays remaining until subscription expiryFree→easyFind products from a specific brandFree→easyFind Toyota listings, regardless of caseFree→easyLabel moderation queue items by urgencyFree→easyLine totals after a percentage discountFree→easyOrders by statusFree→easyProfit margin per productFree→easySelected routes, mid-range priceFree→easyShipped or delivered orders worth over RM 100Free→easyShow 'Unassigned' for branches without a managerFree→easyWallets with a healthy balanceFree→mediumAd click-through conversion rate, per campaignPro→mediumAverage ride duration, by monthPro→mediumBranches beating the network's average growthPro→mediumBuyers active in both January and FebruaryPro→mediumCustomers who never orderedPro→mediumCustomers with no way to reach themPro→mediumDefect rate per production linePro→mediumDrivers rated above averagePro→mediumEmployees who out-earn their managerFree→mediumEvery customer who has banked online or in a branchFree→mediumEvery part, with its supplier (if assigned)Pro→mediumFlag shipments that breached their SLAPro→mediumInactive subscribersPro→mediumLabel TNB bills as on-time, late, or unpaidPro→mediumMonthly fuel salesPro→mediumOutage duration in minutesPro→mediumPivot quarterly sales into columnsPro→mediumPlayers who churned after JanuaryPro→mediumRevenue per routePro→mediumRound fares up, round loyalty points downPro→mediumTop 3 restaurants by ordersPro→mediumTotal fuel spend per monthPro→mediumTotal spend per customerPro→hardBusiest data center in each regionPro→hardDay-over-day change in order volumePro→hardDrivers delayed 3+ days in a rowPro→hardMonth-over-month change in units soldPro→hardPair every employee with their managerPro→hardPivot payment channels into columns, per merchantPro→hardPrevious month's revenuePro→hardRank customers by spendPro→hardRank customers by transaction amount, per branchPro→hardRunning total of daily salesPro→hardSecond most expensive product per categoryPro→hardSplit customers into spending quartilesPro→hardTotal paid, joined across three tablesPro→hardTotal shipped, joined across three tablesPro→