Questions
Status
The 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 minFirst and latest order per customer, on every rowHardSQLSQLHard13 minFiltering on a rankingHardSQLSQLHard14 minRuns of consecutive active daysHardSQLMeta styleSQLMeta styleHard18 minCumulative distinct users by dayHardSQLSQLHard15 minThe latest subscription per account, without a windowHardSQLSQLHard14 minHow long each cancelled subscription lastedHardSQLSQLHard15 minAverage value per unit, without dividing by zeroHardSQLSQLHard13 minEvery warehouse crossed with every itemHardSQLSQLHard15 minCourses nobody has been graded onHardSQLSQLHard14 minPairs of students sharing a courseHardSQLSQLHard15 minMoney in and money out, per accountHardSQLSQLHard14 min