Questions
Status
Countries that buy but never refundMediumSQLSQLMedium11 minSigned up and never came backMediumSQLSQLMedium10 minEvents by planMediumSQLSQLMedium10 minChurned accounts and whenMediumSQLSQLMedium10 minAccounts that subscribed more than onceMediumSQLSQLMedium11 minLive and churned MRR per tierMediumSQLSQLMedium11 minComment count per postMediumSQLSQLMedium10 minAuthors who have never commentedMediumSQLSQLMedium10 minPeople who commented on the same post twiceMediumSQLSQLMedium11 minThe balance of every accountMediumSQLSQLMedium10 minCash movement by monthMediumSQLSQLMedium11 minBoth sides of every transactionMediumSQLSQLMedium11 minWhat each warehouse holdsMediumSQLSQLMedium11 minThe value of each warehouseMediumSQLSQLMedium10 minAverage grade, ungraded excludedMediumSQLSQLMedium12 minGrades earned by more than one studentMediumSQLSQLMedium11 minCredits each student is carryingMediumSQLSQLMedium11 minEach order as a share of the totalMediumSQLSQLMedium12 minEvery date something happenedMediumSQLSQLMedium11 minSort by a status priority, not alphabeticallyMediumSQLSQLMedium12 minDistinct users is not the number of eventsMediumSQLSQLMedium10 minPosts whose title mentions a topicMediumSQLSQLMedium10 minAuthors listed as one lineMediumSQLSQLMedium11 minThe second-highest salary in each departmentHardSQLSQLHard14 minA running total of revenue by dateHardSQLSQLHard14 minEach salary against the department bestHardSQLSQLHard12 minThe most recent hire in each departmentHardSQLSQLHard13 minPaid and refunded side by sideHardSQLSQLHard13 minEach customer's previous order dateHardSQLSQLHard13 minEach customer's largest paid orderHardSQLSQLHard14 minOrdered within thirty days of signing upHardSQLSQLHard13 minSigned up, viewed, purchasedHardSQLMeta styleSQLMeta styleHard14 minUsers active on more than one dayHardSQLSQLHard14 minThe first event of every sessionHardSQLSQLHard15 minDid each user ever purchaseHardSQLSQLHard13 minWho was subscribed on a given dayHardSQLSQLHard15 minEach post's share of its author's viewsHardSQLSQLHard13 minPosts beating their author's averageHardSQLSQLHard13 minTransactions that do not balanceHardSQLStripe styleSQLStripe styleHard14 minA running cash balanceHardSQLSQLHard15 minZero in stock is not the same as no rowHardSQLSQLHard14 minOut of stock everywhereHardSQLSQLHard14 minThe biggest line in each warehouseHardSQLSQLHard13 minRank within each courseHardSQLSQLHard15 minStudents with the most enrolmentsHardSQLSQLHard13 minEnrolled in Databases but not NetworksHardSQLSQLHard13 minThe whole reporting chainHardSQLSQLHard16 minSplit the company into salary quartilesHardSQLSQLHard13 minThe middle salaryHardSQLSQLHard14 minA three-order moving averageHardSQLSQLHard15 min