Interactive SQL exercises
Solved SQL exercises: practise from beginner to advanced
Practise SQL online through progressive business cases. Each exercise provides fictional data, hints, result validation and an explained solution.
62 exercises shown
Time series · LAG · FramesSQL Analyst
Analyze a time series with missing months
Make absent periods visible before calculating evolution and moving average.
Level : AdvancedCompare plansQuality · ROW_NUMBER · TiesSQL Analyst
Deduplicate with a deterministic rule
Choose a canonical email line despite identical dates and multiple sources.
Level : AdvancedCompare plansMargin · Contribution · Multi-tableSQL Analyst
Analyze the margin and real contribution
Link sales and costs to spot a reference that destroys margin.
Level : AdvancedCompare plansKPI quality · level of detail · ReconciliationSQL Analyst
Audit a KPI before publication
Detect why a join with tags inflates revenue, then rebuild the KPI.
Level : AdvancedCompare plansQuality · NULL · ReferencesSQL Analyst
Clean an imperfect dataset before analysis
Profile anomalies, define validity rules and calculate a trackable KPI.
Level : AdvancedCompare plansAutonomous analysis · DecisionSQL Analyst
Conduct an autonomous seller analysis
Choose your own method to compare net income and reimbursements.
Level : AdvancedCompare plansConstraints · IntegritySQL Pro
Guarantee integrity with real constraints
Create and test PRIMARY KEY, FOREIGN KEY, UNIQUE, CHECK, NOT NULL and DEFAULT.
Level : AdvancedCompare plansINSERT · UPDATE · DELETE · UPSERTSQL Pro
Edit data without losing control
Practice writes, their edge cases and an idempotent operation.
Level : AdvancedCompare plansCOMMIT · ROLLBACK · SAVEPOINTSQL Pro
Secure an operation with transactions
Check the status before and after validation, cancellation and partial return.
Level : AdvancedCompare plansVIEW · MATERIALIZED VIEW · REFRESHSQL Pro
Create and maintain reliable views
Check the nature and definition of the objects, not just a few rows returned.
Level : AdvancedCompare plansINDEX · EXPLAIN · SelectivitySQL Pro
Choose an index and read EXPLAIN
Compare a sequential scan and a scan indexed on 5,000 rows.
Level : AdvancedCompare plansFunctions · Signatures · Borderline casesSQL Pro
Write testable PostgreSQL functions
Create a multi-parameter function and test for normal values, NULL, and errors.
Level : AdvancedCompare plansBEFORE · AFTER · OLD · NEW · WHENSQL Pro
Automate an audit with triggers
Test refusal, multi-line audit and trigger condition.
Level : AdvancedCompare plansGRANT · REVOKE · SchematicsSQL Pro
Test roles and permissions positively and negatively
Grant read, deny write, and check actual privileges.
Level : AdvancedCompare plansTraining scenariosThese contextual repetitions reinforce an existing method. They preserve every historical link without pretending to be new canonical problems.Browse 118 scenarios
118 exercises shown
WHERE · ORDER BYSQL Essentials
Isolate actually paid transactions — a regional bookstore · training scenario
Isolate the actually paid operations in the context of a regional bookstore, with a controllable result. You must produce the result, check it on the source data and explain what it allows you to decide in this network of bookstores.
Level : BeginnerCompare plansGROUP BY · SUMSQL Essentials
Compare value by city — a regional bookstore · training scenario
Compare the value by city in the context of a regional bookstore, with a controllable result. You must produce the result, check it on the source data and explain what it allows you to decide in this network of bookstores.
Level : BeginnerCompare plansCASESQL Essentials
Prioritize amounts — a regional bookstore · training scenario
Prioritize amounts in the context of a regional bookstore, with a controllable result. You must produce the result, check it on the source data and explain what it allows you to decide in this network of bookstores.
Level : BeginnerCompare plansCOUNT · GROUP BYSQL Essentials
Count volume by status — a regional bookstore · training scenario
Count volume by status in the context of a regional bookstore, with a controllable result. You must produce the result, check it on the source data and explain what it allows you to decide in this network of bookstores.
Level : BeginnerCompare plansDISTINCTSQL Essentials
List active categories — a regional bookstore · training scenario
List active categories in the context of a regional bookstore, with a controllable result. You must produce the result, check it on the source data and explain what it allows you to decide in this network of bookstores.
Level : BeginnerCompare plansDATE_TRUNC · SUMSQL Essentials
Follow monthly progress — a regional bookstore · training scenario
Monitor monthly developments in the context of a regional bookstore, with a controllable result. You must produce the result, check it on the source data and explain what it allows you to decide in this network of bookstores.
Level : BeginnerCompare plansWHERE · ORDER BYSQL Essentials
Isolating actually paid operations — a network of clinics · training scenario
Isolate actually paid operations in the context of a network of clinics, with a controllable result. You must produce the result, check it on the source data and explain what it allows you to decide in this network of clinics.
Level : BeginnerCompare plansGROUP BY · SUMSQL Essentials
Compare value by city — a network of clinics · training scenario
Compare the value by city in the context of a network of clinics, with a controllable result. You must produce the result, check it on the source data and explain what it allows you to decide in this network of clinics.
Level : BeginnerCompare plansCASESQL Essentials
Prioritize amounts — a network of clinics · training scenario
Prioritize amounts in the context of a network of clinics, with a controllable outcome. You must produce the result, check it on the source data and explain what it allows you to decide in this network of clinics.
Level : BeginnerCompare plansCOUNT · GROUP BYSQL Essentials
Count volume by status — a network of clinics · training scenario
Count volume by status in the context of a network of clinics, with a controllable result. You must produce the result, check it on the source data and explain what it allows you to decide in this network of clinics.
Level : BeginnerCompare plansDISTINCTSQL Essentials
List active categories — a network of clinics · training scenario
List active categories in the context of a network of clinics, with a controllable result. You must produce the result, check it on the source data and explain what it allows you to decide in this network of clinics.
Level : BeginnerCompare plansDATE_TRUNC · SUMSQL Essentials
Monitor monthly progress — a network of clinics · training scenario
Monitor monthly developments in the context of a network of clinics, with a controllable result. You must produce the result, check it on the source data and explain what it allows you to decide in this network of clinics.
Level : BeginnerCompare plansWHERE · ORDER BYSQL Essentials
Isolating actually paid transactions — a training organization · training scenario
Isolate the operations actually paid in the context of a training organization, with a controllable result. You must produce the result, check it on the source data and explain what it allows to decide in this training organization.
Level : BeginnerCompare plansGROUP BY · SUMSQL Essentials
Compare value by city — a training organization · training scenario
Compare the value per city in the context of a training organization, with a controllable result. You must produce the result, check it on the source data and explain what it allows to decide in this training organization.
Level : BeginnerCompare plansCASESQL Essentials
Prioritize amounts — a training organization · training scenario
Prioritize amounts in the context of a training organization, with a controllable result. You must produce the result, check it on the source data and explain what it allows to decide in this training organization.
Level : BeginnerCompare plansCOUNT · GROUP BYSQL Essentials
Count volume by status — a training organization · training scenario
Count the volume by status in the context of a training organization, with a controllable result. You must produce the result, check it on the source data and explain what it allows to decide in this training organization.
Level : BeginnerCompare plansDISTINCTSQL Essentials
List active categories — a training organization · training scenario
List active categories in the context of a training organization, with a controllable result. You must produce the result, check it on the source data and explain what it allows to decide in this training organization.
Level : BeginnerCompare plansDATE_TRUNC · SUMSQL Essentials
Monitor monthly progress — a training organization · training scenario
Monitor monthly progress in the context of a training organization, with a controllable result. You must produce the result, check it on the source data and explain what it allows to decide in this training organization.
Level : BeginnerCompare plansWHERE · ORDER BYSQL Essentials
Isolate actual paid transactions — a delivery company · training scenario
Isolate actual paid operations in the context of a delivery business, with a controllable outcome. You must produce the result, check it on the source data and explain what it allows you to decide in this delivery company.
Level : BeginnerCompare plansGROUP BY · SUMSQL Essentials
Compare value by city — a delivery company · training scenario
Compare the value by city in the context of a delivery company, with a controllable result. You must produce the result, check it on the source data and explain what it allows you to decide in this delivery company.
Level : BeginnerCompare plansCASESQL Essentials
Prioritize amounts — a delivery company · training scenario
Prioritize amounts in the context of a delivery business, with a controllable outcome. You must produce the result, check it on the source data and explain what it allows you to decide in this delivery company.
Level : BeginnerCompare plansCOUNT · GROUP BYSQL Essentials
Count volume by status — a delivery company · training scenario
Count volume by status in the context of a delivery business, with a controllable result. You must produce the result, check it on the source data and explain what it allows you to decide in this delivery company.
Level : BeginnerCompare plansDISTINCTSQL Essentials
List active categories — a delivery company · training scenario
List active categories in the context of a delivery business, with a controllable result. You must produce the result, check it on the source data and explain what it allows you to decide in this delivery company.
Level : BeginnerCompare plansDATE_TRUNC · SUMSQL Essentials
Monitor monthly progress — a delivery company · training scenario
Monitor monthly progress in the context of a delivery company, with a controllable result. You must produce the result, check it on the source data and explain what it allows you to decide in this delivery company.
Level : BeginnerCompare plansTwo focused paths reuse these experiences.
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