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5,893 curated questions across every arena — browse by topic, then jump into a live 3-minute battle to put them to the test.
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45 challenges matching your filters
Clear topic filter- Multiple ChoiceHard
[SQL] Atomicity Transaction guarantees
qasqlsqlqa - Multiple ChoiceHard
[SQL] Isolation Transaction guarantees
qasqlsqlqa - Multiple ChoiceHard
[SQL] Durability Transaction guarantees
qasqlsqlqa - Multiple ChoiceHard
[SQL] Consistency Transaction guarantees
qasqlsqlqa - Multiple ChoiceHard
[SQL] Serializable Transaction guarantees
qasqlsqlqa - Multiple ChoiceIntermediate
[SQL] Readability WITH clause for readability
qasqlsqlqa - Multiple ChoiceIntermediate
[SQL] Recursive WITH clause for readability
qasqlsqlqa - Multiple ChoiceIntermediate
[SQL] Multiple WITH clause for readability
qasqlsqlqa - Multiple ChoiceIntermediate
[SQL] Materialized WITH clause for readability
qasqlsqlqa - Multiple ChoiceIntermediate
[SQL] Chained WITH clause for readability
qasqlsqlqa - Multiple ChoiceIntermediate
[SQL] B-tree Speed up queries via B-tree/hash
qasqlsqlqa - Multiple ChoiceIntermediate
[SQL] Covering Speed up queries via B-tree/hash
qasqlsqlqa - Multiple ChoiceIntermediate
[SQL] FK index Speed up queries via B-tree/hash
qasqlsqlqa - Multiple ChoiceIntermediate
[SQL] Partial Speed up queries via B-tree/hash
qasqlsqlqa - Multiple ChoiceIntermediate
[SQL] GIN/GiST Speed up queries via B-tree/hash
qasqlsqlqa - Multiple ChoiceBeginner
[SQL] INNER Combine rows from multiple tables
qasqlsqlqa - Multiple ChoiceBeginner
[SQL] LEFT Combine rows from multiple tables
qasqlsqlqa - Multiple ChoiceBeginner
[SQL] CROSS Combine rows from multiple tables
qasqlsqlqa - Multiple ChoiceBeginner
[SQL] SELF Combine rows from multiple tables
qasqlsqlqa - Multiple ChoiceBeginner
[SQL] LATERAL Combine rows from multiple tables
qasqlsqlqa - Multiple ChoiceHard
[SQL] Pessimistic Concurrency control
qasqlsqlqa - Multiple ChoiceHard
[SQL] Deadlock Concurrency control
qasqlsqlqa - Multiple ChoiceHard
[SQL] Optimistic Concurrency control
qasqlsqlqa - Multiple ChoiceHard
[SQL] SKIP LOCKED Concurrency control
qasqlsqlqa - Multiple ChoiceHard
[SQL] NOWAIT Concurrency control
qasqlsqlqa - Multiple ChoiceHard
[SQL] Snapshot Multi-Version Concurrency Control
qasqlsqlqa - Multiple ChoiceHard
[SQL] xmin/xmax Multi-Version Concurrency Control
qasqlsqlqa - Multiple ChoiceHard
[SQL] Vacuum Multi-Version Concurrency Control
qasqlsqlqa - Multiple ChoiceHard
[SQL] XID wraparound Multi-Version Concurrency Control
qasqlsqlqa - Multiple ChoiceHard
[SQL] HOT Multi-Version Concurrency Control
qasqlsqlqa - Multiple ChoiceIntermediate
[SQL] 1NF Reduce redundancy
qasqlsqlqa - Multiple ChoiceIntermediate
[SQL] 2NF Reduce redundancy
qasqlsqlqa - Multiple ChoiceIntermediate
[SQL] 3NF Reduce redundancy
qasqlsqlqa - Multiple ChoiceIntermediate
[SQL] BCNF Reduce redundancy
qasqlsqlqa - Multiple ChoiceIntermediate
[SQL] Denormalize Reduce redundancy
qasqlsqlqa - Multiple ChoiceHard
[SQL] ROW_NUMBER OVER() clause
qasqlsqlqa - Multiple ChoiceHard
[SQL] RANK OVER() clause
qasqlsqlqa - Multiple ChoiceHard
[SQL] LAG/LEAD OVER() clause
qasqlsqlqa - Multiple ChoiceHard
[SQL] Running sum OVER() clause
qasqlsqlqa - Multiple ChoiceHard
[SQL] PARTITION BY OVER() clause
qasqlsqlqa - Code AnalysisBeginner
NULL comparison bug
system-designdatabasessql - Code AnalysisBeginner
Index-killing function on column
indexingsargabilitysql - Code AnalysisIntermediate
Non-Atomic Balance Check SQL
sqlconcurrencytoctou - Code AnalysisHard
Reconciliation Missing Rows Bug
reconciliationsqlouter-join - Code AnalysisIntermediate
Tenant filter missing in query
multi-tenantisolationsql
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