SQL MCQs | Database Interview MCQ Questions and Answers

Test your knowledge of Database - [ SQL ] section with these interactive multiple-choice questions.

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141. What is composite partitioning?

  • a) Combining multiple partitioning methods
  • b) Splitting tables across servers
  • c) Merging partitions dynamically
  • d) Encrypting partitioned data
Answer: A - Example: RANGE partitioning with LIST subpartitions.

142. Which in-memory database stores data primarily in RAM?

  • a) Redis
  • b) MemSQL
  • c) VoltDB
  • d) All of the above
Answer: D - All are designed for ultra-low latency in-memory processing.

143. What is the purpose of AUTO_SCALING in cloud databases?

  • a) Adjusts resources based on workload
  • b) Optimizes query plans
  • c) Balances partitions
  • d) Migrates data automatically
Answer: A - Scales compute/storage up/down to match demand.

144. Which AI feature suggests SQL query improvements?

  • a) Query Store Hints
  • b) Automatic Tuning
  • c) Database Advisor
  • d) All of the above
Answer: D - Modern DBMS use AI to recommend indexes and plan fixes.

145. What is quantum database indexing?

  • a) Theoretical indexing using qubits
  • b) Encrypted index structures
  • c) Distributed hash tables
  • d) Blockchain-based indexing
Answer: A - Emerging research area for quantum computing advantages.

146. Which statement creates a partitioned table?

  • a) CREATE TABLE...PARTITION BY
  • b) MAKE PARTITIONED TABLE
  • c) ADD PARTITION TO TABLE
  • d) SPLIT TABLE
Answer: A - Syntax varies (Oracle: PARTITION BY RANGE, SQL Server: ON SCHEMA).

147. What is the purpose of database-as-a-service (DBaaS)?

  • a) Managed database hosting
  • b) On-demand provisioning
  • c) Automated maintenance
  • d) All of the above
Answer: D - Cloud providers handle installation, patching, and backups.

148. Which SQL feature predicts query performance?

  • a) Query Store
  • b) Execution Plan Analysis
  • c) What-If Analysis
  • d) All of the above
Answer: D - Tools to estimate resource usage before execution.

149. What is the purpose of SQL's HYPERLOGLOG functions?

  • a) Approximate distinct counts
  • b) Encrypted aggregations
  • c) Geometric calculations
  • d) Machine learning
Answer: A - Probabilistic algorithm for big data cardinality estimation.

150. Which database offers multi-write replication?

  • a) CockroachDB
  • b) YugabyteDB
  • c) Amazon Aurora
  • d) All of the above
Answer: D - Allow writes to multiple nodes with conflict resolution.

151. What is the purpose of the SQL SKIP LOCKED option?

  • a) Bypasses locked rows
  • b) Releases locks early
  • c) Delays locking
  • d) Logs lock attempts
Answer: A - Enables work queue patterns by skipping contended rows.

152. Which statement creates a memory-optimized filegroup?

  • a) ALTER DATABASE ADD FILEGROUP...CONTAINS MEMORY_OPTIMIZED_DATA
  • b) CREATE IN-MEMORY STORAGE
  • c) MAKE MEMORY FILEGROUP
  • d) ENABLE IN-MEMORY TABLES
Answer: A - Required for In-Memory OLTP in SQL Server.

153. What is the purpose of the SQL TRANSLATE() function?

  • a) Character-by-character replacement
  • b) Language translation
  • c) Data conversion
  • d) Query transformation
Answer: A - More powerful than REPLACE() for multiple substitutions.

154. Which database feature enables zero-ETL analytics?

  • a) Direct query over external data
  • b) Materialized views
  • c) Linked servers
  • d) All of the above
Answer: D - Techniques to analyze data without extraction pipelines.

155. What is the purpose of the SQL UNISTR() function?

  • a) Handles Unicode escape sequences
  • b) Validates UTF-8
  • c) Universal string storage
  • d) Case conversion
Answer: A - Converts \XXXX sequences to Unicode characters.

156. Which database provides probabilistic data structures?

  • a) Redis (Bloom filters)
  • b) PostgreSQL (extension)
  • c) Oracle (approximate counts)
  • d) All of the above
Answer: D - Efficient for membership testing and cardinality estimation.

157. What is the purpose of the SQL GROUPING SETS clause?

  • a) Multiple grouping levels in one query
  • b) Defines partition sets
  • c) Groups spatial data
  • d) Creates sets for machine learning
Answer: A - Alternative to UNION ALL with different GROUP BY clauses.

158. Which statement creates a database firewall rule?

  • a) CREATE FIREWALL RULE
  • b) ADD NETWORK POLICY
  • c) ENABLE ACCESS CONTROL
  • d) DEFINE SECURITY GROUP
Answer: A - Cloud databases allow IP-based access restrictions.

159. What is the purpose of the SQL BIT_COUNT() function?

  • a) Counts set bits in binary values
  • b) Calculates storage size
  • c) Estimates cardinality
  • d) Validates checksums
Answer: A - Useful for bitmap/hamming distance calculations.

160. Which database feature enables time-bound queries?

  • a) Time Travel (Snowflake)
  • b) Flashback Query (Oracle)
  • c) Temporal Tables (SQL Server)
  • d) All of the above
Answer: D - Different implementations of historical data access.
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