Browse by SQL concept

Drill the exact topic you want to practice

Every mission on caseSQL is tagged with the SQL concepts it practices. Pick a concept below to see every mission that drills it — across all four career paths. Great for targeted practice before an interview, or when you want to shore up a weak spot.

119 concepts · 100 missions

GROUP BY10 missions
Marketing·StarterWhere are our customers?Mission 4 →Marketing·StarterWhat are people buying?Mission 5 →Marketing·EasyWhich coupon is pulling its weight?Mission 7 →Marketing·MediumWhat's our average order value per campaign?Mission 15 →Healthcare·StarterEncounters by departmentMission 4 →Healthcare·StarterInsurance mixMission 5 →Healthcare·EasyTop 10 diagnosesMission 7 →Finance·EasyTop 10 vendors by YTD spendMission 7 →Finance·EasyMonthly expense by departmentMission 9 →Finance·MediumRevenue seasonalityMission 13 →
LIMIT7 missions
Marketing·StarterWelcome — preview the customer tableMission 1 →Marketing·StarterWhere are our customers?Mission 4 →Marketing·MediumTop 5 customers by spendMission 13 →Healthcare·StarterMeet the patientsMission 1 →Healthcare·EasyTop 10 diagnosesMission 7 →Finance·StarterChart of accounts quick lookMission 1 →Finance·EasyTop 10 vendors by YTD spendMission 7 →
CASE6 missions
Marketing·MediumWhich campaign has the best ROI?Mission 12 →Marketing·HardNormalize the gender messMission 18 →BI·StarterBoard deck needs revenue by quarterMission 1 →Healthcare·MediumReadmission rate by insurance typeMission 13 →Finance·EasyGross margin by quarterMission 10 →Finance·MediumAre we over budget this March?Mission 11 →
JOINs6 missions
Marketing·EasyWhich channel gets the best open rate?Mission 9 →Marketing·MediumWhich campaign drove the most revenue?Mission 11 →Marketing·MediumRevenue by stateMission 14 →BI·StarterWho is hitting their sales targets?Mission 2 →BI·EasyHow many unique customers per region?Mission 9 →Finance·MediumAre we over budget this March?Mission 11 →
SELECT6 missions
Marketing·StarterWelcome — preview the customer tableMission 1 →Marketing·StarterWhat campaigns are running?Mission 2 →Healthcare·StarterMeet the patientsMission 1 →Healthcare·StarterHow many departments do we have?Mission 2 →Finance·StarterChart of accounts quick lookMission 1 →Finance·StarterWho owns which cost center?Mission 2 →
Subqueries6 missions
Marketing·EasyHow many customers are repeat buyers?Mission 10 →Marketing·HardCustomers who never opened an emailMission 20 →Marketing·ExpertCustomers buying across categoriesMission 23 →BI·StarterProduct mix is shiftingMission 3 →BI·EasyFind reps outselling their department averageMission 8 →Finance·MediumOverspend flagsMission 12 →
Bucketing5 missions
BI·EasyDiscount tiers need a reality checkMission 6 →BI·MediumTenure and salary — any correlation?Mission 15 →Healthcare·MediumED throughput — the real numbersMission 12 →Finance·HardBudget attainment heat mapMission 20 →Finance·ExpertLate-posting analysisMission 21 →
CTE5 missions
Healthcare·ExpertReadmission cohort deep diveMission 21 →Healthcare·ExpertPatient satisfaction trend with moving averageMission 22 →Healthcare·ExpertTop diagnoses year-over-yearMission 23 →Finance·ExpertLate-posting analysisMission 21 →Finance·ExpertNew vs. recurring vendor spendMission 22 →
Data quality5 missions
Marketing·StarterWelcome — preview the customer tableMission 1 →Healthcare·StarterMeet the patientsMission 1 →Healthcare·StarterInsurance mixMission 5 →Finance·StarterChart of accounts quick lookMission 1 →Finance·StarterWhat account types do we have?Mission 3 →
LEFT JOIN5 missions
Marketing·EasyHow many customers never bought anything?Mission 8 →Marketing·MediumWhich campaign has the best ROI?Mission 12 →BI·StarterWhich region should we expand next?Mission 4 →Healthcare·EasyDepartments with no encountersMission 9 →Healthcare·HardDepartment utilization ratesMission 19 →
TRIM5 missions
Marketing·HardClean up the traffic sourcesMission 17 →Marketing·ExpertFix the product category messMission 22 →Healthcare·EasyTop 10 diagnosesMission 7 →Healthcare·ExpertTop diagnoses year-over-yearMission 23 →Finance·EasyVendor duplicates auditMission 6 →
WHERE5 missions
Marketing·EasyWhich coupon is pulling its weight?Mission 7 →Healthcare·EasyED wait time overviewMission 8 →Healthcare·EasyProvider roster with red flagsMission 10 →Finance·StarterHow much did we spend on SaaS in 2025?Mission 4 →Finance·EasyUn-posted journal cleanupMission 8 →
Aggregation4 missions
Marketing·StarterHow many emails did we send?Mission 3 →BI·StarterBoard deck needs revenue by quarterMission 1 →Healthcare·StarterTotal encounter volumeMission 3 →Finance·EasyGross margin by quarterMission 10 →
COUNT DISTINCT4 missions
Marketing·EasyCount unique customersMission 6 →Marketing·ExpertCustomers buying across categoriesMission 23 →BI·EasyWhich categories are actually selling well?Mission 7 →BI·EasyHow many unique customers per region?Mission 9 →
Date arithmetic4 missions
BI·MediumTenure and salary — any correlation?Mission 15 →Healthcare·MediumAverage length of stay by departmentMission 11 →Healthcare·MediumPatient age at admissionMission 15 →Finance·ExpertLate-posting analysisMission 21 →
GROUP BY HAVING4 missions
Marketing·ExpertSomething's off with our numbersMission 21 →Healthcare·MediumDuplicate patient auditMission 14 →Finance·EasyVendor duplicates auditMission 6 →Finance·HardDuplicate payment detectionMission 16 →
HAVING4 missions
Marketing·EasyHow many customers are repeat buyers?Mission 10 →BI·EasyWhich categories are actually selling well?Mission 7 →Healthcare·HardProvider complication ratesMission 20 →Finance·MediumOverspend flagsMission 12 →
JOIN4 missions
Healthcare·StarterEncounters by departmentMission 4 →Healthcare·EasyWho’s currently admitted?Mission 6 →Healthcare·EasyProvider roster with red flagsMission 10 →Finance·StarterMarch 2025 expense totalMission 5 →
LAG()4 missions
BI·MediumMonthly revenue trend with growth rateMission 13 →BI·ExpertYear-over-year revenue by quarterMission 21 →Healthcare·HardMonth-over-month encounter trendMission 18 →Finance·HardYear-over-year revenue growthMission 18 →
Percentages4 missions
Marketing·EasyWhich channel gets the best open rate?Mission 9 →Marketing·ExpertTotal refund impactMission 24 →BI·StarterProduct mix is shiftingMission 3 →Healthcare·MediumReadmission rate by insurance typeMission 13 →
Self-join4 missions
BI·MediumWho reports to whom?Mission 12 →Healthcare·MediumDuplicate patient auditMission 14 →Healthcare·ExpertReadmission cohort deep diveMission 21 →Finance·HardDuplicate payment detectionMission 16 →
SUM4 missions
Marketing·StarterWhat are people buying?Mission 5 →Marketing·MediumWhich campaign drove the most revenue?Mission 11 →Finance·StarterHow much did we spend on SaaS in 2025?Mission 4 →Finance·StarterMarch 2025 expense totalMission 5 →
Window functions4 missions
BI·MediumRank the sales teamMission 11 →BI·ExpertHire cohort performance analysisMission 23 →Healthcare·HardRank specialties by encounter volumeMission 16 →Finance·HardCost center rank by 2025 OpExMission 19 →
AVG3 missions
Marketing·MediumWhat's our average order value per campaign?Mission 15 →Healthcare·EasyED wait time overviewMission 8 →Finance·MediumRevenue seasonalityMission 13 →
CASE WHEN3 missions
BI·EasyDiscount tiers need a reality checkMission 6 →BI·EasyTag every sale by sizeMission 10 →Healthcare·MediumED throughput — the real numbersMission 12 →
COUNT3 missions
Marketing·StarterHow many emails did we send?Mission 3 →Healthcare·StarterTotal encounter volumeMission 3 →Healthcare·StarterInsurance mixMission 5 →
Exploration3 missions
Marketing·StarterWhat campaigns are running?Mission 2 →Healthcare·StarterHow many departments do we have?Mission 2 →Finance·StarterWho owns which cost center?Mission 2 →
IS NULL3 missions
Marketing·EasyHow many customers never bought anything?Mission 8 →Marketing·HardHow many organic purchases?Mission 19 →Healthcare·EasyDepartments with no encountersMission 9 →
Multi-JOIN3 missions
Marketing·ExpertThe full campaign scorecardMission 25 →Healthcare·MediumED throughput — the real numbersMission 12 →Finance·EasyMonthly expense by departmentMission 9 →
Multi-table JOIN3 missions
Marketing·MediumTop 5 customers by spendMission 13 →BI·EasyTag every sale by sizeMission 10 →BI·HardThree-table join: who sold what where?Mission 18 →
NULL handling3 missions
BI·StarterWhich region should we expand next?Mission 4 →BI·EasyDiscount tiers need a reality checkMission 6 →Healthcare·MediumAverage length of stay by departmentMission 11 →
ORDER BY3 missions
Marketing·StarterWhere are our customers?Mission 4 →Healthcare·StarterEncounters by departmentMission 4 →Finance·EasyTop 10 vendors by YTD spendMission 7 →
PARTITION BY3 missions
BI·HardTop 2 products per categoryMission 16 →BI·ExpertYear-over-year revenue by quarterMission 21 →Finance·HardYear-over-year revenue growthMission 18 →
RANK()3 missions
BI·MediumRank the sales teamMission 11 →Healthcare·HardRank specialties by encounter volumeMission 16 →Finance·HardCost center rank by 2025 OpExMission 19 →
Window frame3 missions
BI·HardRunning revenue total by monthMission 20 →BI·ExpertThree-month moving averageMission 22 →Finance·MediumRunning cash burnMission 15 →
Attribution2 missions
Marketing·HardIs our email actually working?Mission 16 →Marketing·HardHow many organic purchases?Mission 19 →
Capstone2 missions
Healthcare·ExpertThe CMS Quality DashboardMission 25 →Finance·ExpertBoard-ready P&L capstoneMission 25 →
CASE aggregation2 missions
Marketing·ExpertTotal refund impactMission 24 →Finance·MediumRefund leakageMission 14 →
CASE pivot2 missions
BI·MediumPivot revenue by category and yearMission 14 →Finance·HardBudget attainment heat mapMission 20 →
COALESCE2 missions
BI·StarterWhich region should we expand next?Mission 4 →Healthcare·HardDepartment utilization ratesMission 19 →
Correlated subquery2 missions
BI·HardFind products with no sales last quarterMission 17 →Healthcare·HardProvider complication ratesMission 20 →
Data quality audit2 missions
Marketing·ExpertFix the product category messMission 22 →BI·StarterThe dashboard numbers don't add upMission 5 →
Date extraction2 missions
Healthcare·HardMonth-over-month encounter trendMission 18 →Finance·MediumRevenue seasonalityMission 13 →
Date truncation2 missions
BI·MediumMonthly revenue trend with growth rateMission 13 →Finance·EasyMonthly expense by departmentMission 9 →
Date window2 missions
Healthcare·ExpertReadmission cohort deep diveMission 21 →Finance·HardDuplicate payment detectionMission 16 →
LOWER2 missions
Marketing·HardClean up the traffic sourcesMission 17 →Finance·EasyVendor duplicates auditMission 6 →
LOWER()2 missions
Healthcare·MediumReadmission rate by insurance typeMission 13 →Healthcare·HardRank specialties by encounter volumeMission 16 →
Multi-CTE pipeline2 missions
Healthcare·ExpertThe CMS Quality DashboardMission 25 →Finance·ExpertBoard-ready P&L capstoneMission 25 →
NTILE()2 missions
BI·ExpertPercentile ranking across the sales forceMission 24 →Finance·ExpertPercentile ranking of cost centersMission 24 →
PERCENT_RANK()2 missions
BI·ExpertPercentile ranking across the sales forceMission 24 →Finance·ExpertPercentile ranking of cost centersMission 24 →
ROW_NUMBER()2 missions
BI·MediumRank the sales teamMission 11 →BI·HardTop 2 products per categoryMission 16 →
SUM() OVER2 missions
BI·HardRunning revenue total by monthMission 20 →Finance·MediumRunning cash burnMission 15 →
YoY2 missions
BI·ExpertYear-over-year revenue by quarterMission 21 →Finance·HardYear-over-year revenue growthMission 18 →
% change1 mission
Healthcare·HardMonth-over-month encounter trendMission 18 →
Active filtering1 mission
BI·StarterWho is hitting their sales targets?Mission 2 →
Advanced analytics1 mission
BI·ExpertThe executive summary queryMission 25 →
Ambiguity1 mission
Marketing·EasyCount unique customersMission 6 →
Attainment1 mission
BI·StarterWho is hitting their sales targets?Mission 2 →
Audit trail1 mission
Finance·EasyUn-posted journal cleanupMission 8 →
AVG() OVER()1 mission
Healthcare·HardED wait times by day of weekMission 17 →
Budget vs actual1 mission
Finance·MediumAre we over budget this March?Mission 11 →
CASE buckets1 mission
Healthcare·MediumPatient age at admissionMission 15 →
Category normalization1 mission
BI·StarterProduct mix is shiftingMission 3 →
Cohort analysis1 mission
BI·ExpertHire cohort performance analysisMission 23 →
Cohort logic1 mission
Finance·ExpertNew vs. recurring vendor spendMission 22 →
Comparison1 mission
BI·EasyFind reps outselling their department averageMission 8 →
Comprehensive report1 mission
Healthcare·ExpertDepartment scorecardMission 24 →
Correlated subqueries1 mission
BI·HardCorrelated check: reps beating their own averageMission 19 →
Cross-tab1 mission
BI·MediumPivot revenue by category and yearMission 14 →
CTEs1 mission
Marketing·ExpertThe full campaign scorecardMission 25 →
Cumulative share1 mission
Finance·HardRevenue concentrationMission 17 →
Data cleaning1 mission
Marketing·HardNormalize the gender messMission 18 →
Date cohorts1 mission
Finance·ExpertVendor onboarding cohortsMission 23 →
Date filter1 mission
Finance·StarterHow much did we spend on SaaS in 2025?Mission 4 →
Date math1 mission
Marketing·HardIs our email actually working?Mission 16 →
Date parsing1 mission
BI·StarterBoard deck needs revenue by quarterMission 1 →
Date range1 mission
Finance·StarterMarch 2025 expense totalMission 5 →
Deduplication1 mission
Marketing·ExpertSomething's off with our numbersMission 21 →
Denormalization1 mission
BI·HardThree-table join: who sold what where?Mission 18 →
DISTINCT1 mission
Finance·StarterWhat account types do we have?Mission 3 →
Division1 mission
Marketing·MediumWhich campaign has the best ROI?Mission 12 →
EXTRACT(DOW)1 mission
Healthcare·HardED wait times by day of weekMission 17 →
Filtering1 mission
Finance·HardCost center rank by 2025 OpExMission 19 →
First-seen1 mission
Finance·ExpertNew vs. recurring vendor spendMission 22 →
Format handling1 mission
Healthcare·MediumPatient age at admissionMission 15 →
Full report1 mission
Marketing·ExpertThe full campaign scorecardMission 25 →
Geographic analysis1 mission
Marketing·MediumRevenue by stateMission 14 →
Growth1 mission
BI·MediumMonthly revenue trend with growth rateMission 13 →
Hierarchy1 mission
BI·MediumWho reports to whom?Mission 12 →
INTERVAL1 mission
Marketing·HardIs our email actually working?Mission 16 →
Investigation1 mission
BI·StarterThe dashboard numbers don't add upMission 5 →
LAG1 mission
Healthcare·ExpertPatient satisfaction trend with moving averageMission 22 →
LAG PARTITION BY1 mission
Healthcare·ExpertTop diagnoses year-over-yearMission 23 →
MAX1 mission
Healthcare·EasyED wait time overviewMission 8 →
MIN1 mission
Healthcare·EasyED wait time overviewMission 8 →
Moving average1 mission
BI·ExpertThree-month moving averageMission 22 →
Multi-technique1 mission
BI·ExpertThe executive summary queryMission 25 →
Multiple CTEs1 mission
Healthcare·ExpertDepartment scorecardMission 24 →
Negative amounts1 mission
Finance·MediumRefund leakageMission 14 →
Normalization1 mission
Marketing·HardClean up the traffic sourcesMission 17 →
NOT EXISTS1 mission
BI·HardFind products with no sales last quarterMission 17 →
NOT IN1 mission
Marketing·HardCustomers who never opened an emailMission 20 →
NULL filtering1 mission
Marketing·EasyWhich coupon is pulling its weight?Mission 7 →
OR logic1 mission
Healthcare·EasyProvider roster with red flagsMission 10 →
PERCENT_RANK1 mission
Finance·HardRevenue concentrationMission 17 →
Pivot1 mission
Finance·ExpertBoard-ready P&L capstoneMission 25 →
Posted flag1 mission
Finance·EasyUn-posted journal cleanupMission 8 →
Rate calc1 mission
Healthcare·HardProvider complication ratesMission 20 →
Ratio1 mission
Finance·EasyGross margin by quarterMission 10 →
Refund filtering1 mission
Marketing·MediumWhich campaign drove the most revenue?Mission 11 →
Refunds1 mission
Marketing·StarterWhat are people buying?Mission 5 →
Retention logic1 mission
Finance·ExpertVendor onboarding cohortsMission 23 →
ROWS BETWEEN1 mission
Healthcare·ExpertPatient satisfaction trend with moving averageMission 22 →
Subquery1 mission
Healthcare·HardDepartment utilization ratesMission 19 →
Top-N1 mission
BI·HardTop 2 products per categoryMission 16 →
Variance1 mission
Finance·MediumOverspend flagsMission 12 →
Variance %1 mission
Finance·HardBudget attainment heat mapMission 20 →
WHERE IS NULL1 mission
Healthcare·EasyWho’s currently admitted?Mission 6 →
Window frames1 mission
Healthcare·ExpertThe CMS Quality DashboardMission 25 →