Databases for Web Applications

Q1. What is MySQL?

1. A.A CSS framework for responsive web page layouts
2. B.A web server for hosting application endpoints
3. C.An open-source relational database management system✓ Correct
4. D.A JavaScript library for building web interfaces

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Q2. What is MongoDB?

1. A.A NoSQL document database storing JSON-like data✓ Correct
2. B.A CSS framework for building styled components
3. C.A web server for serving static content files
4. D.A SQL relational database using table schemas

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Q3. What does SQL stand for?

1. A.Simple Query Language
2. B.Structured Query Language✓ Correct
3. C.Server Query Logic
4. D.Standard Question Language

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Q4. Which SQL command retrieves data?

1. A.RETRIEVE
2. B.FETCH
3. C.GET
4. D.SELECT✓ Correct

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Q5. What is a primary key?

1. A.The first column created in a database table
2. B.A password used for database authentication
3. C.A unique identifier for each record in a table✓ Correct
4. D.A foreign key linking to another related table

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Q6. What SQL command inserts new data?

1. A.CREATE INTO
2. B.ADD INTO
3. C.INSERT INTO✓ Correct
4. D.PUT INTO

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Q7. What is a table in a relational database?

1. A.A JavaScript object for storing key-value pairs
2. B.A CSS grid for laying out page components
3. C.An HTML table element for displaying data
4. D.A structured collection of rows and columns✓ Correct

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Q8. What is PostgreSQL?

1. A.A CSS preprocessor for advanced style features
2. B.An advanced open-source relational database system✓ Correct
3. C.A JavaScript framework for building web apps
4. D.A web browser for viewing internet content

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Q9. What SQL command deletes data?

1. A.DESTROY
2. B.DELETE✓ Correct
3. C.DROP DATA
4. D.REMOVE

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Q10. What is a database schema?

1. A.The structure defining data organization and relations✓ Correct
2. B.An HTML template for rendering dynamic page content
3. C.A JavaScript object for storing config data
4. D.A CSS layout blueprint for page structure

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Q11. What is a foreign key?

1. A.A column linking two tables via another primary key✓ Correct
2. B.A key imported from another country or locale
3. C.An encrypted key used for securing data at rest
4. D.A backup key for recovering lost database records

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Q12. What is database indexing?

1. A.Creating structures that speed up data retrieval✓ Correct
2. B.Numbering database rows in sequential order
3. C.Organizing files on disk for better storage
4. D.A CSS technique for ordering layout elements

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Q13. What is a JOIN in SQL?

1. A.A JavaScript method for merging arrays together
2. B.Combining multiple CSS files into a single bundle
3. C.A string concatenation operator for joining text
4. D.A clause combining rows from tables based on columns✓ Correct

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Q14. What is the difference between INNER JOIN and LEFT JOIN?

1. A.LEFT JOIN returns only the matching rows from both sources
2. B.They are identical in their result sets
3. C.INNER JOIN includes NULL values from non-matching entries
4. D.INNER returns matches only; LEFT returns all left rows plus matches✓ Correct

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Q15. What is database normalization?

1. A.Normalizing CSS values for cross-browser consistency
2. B.Formatting JSON data for human-readable pretty output
3. C.Making data look normal in the display output
4. D.Organizing data to reduce redundancy via normal forms✓ Correct

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Q16. What is an ODM?

1. A.A JavaScript operator for object comparison
2. B.A CSS framework for responsive layout design
3. C.A type of relational database engine
4. D.Object-Document Mapper for objects and NoSQL docs✓ Correct

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Q17. What is a transaction in databases?

1. A.A CSS transition for animating property changes
2. B.A data transfer between server and client machines
3. C.A sequence of operations treated as a single unit✓ Correct
4. D.A financial payment between two bank accounts

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Q18. What are ACID properties?

1. A.A type of document-oriented database engine system for storing data
2. B.A security protocol for encrypting network traffic between services
3. C.Atomicity, Consistency, Isolation, Durability for reliable transactions✓ Correct
4. D.A chemistry concept related to pH levels

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Q19. What is Redis commonly used for?

1. A.As a primary database for all application data
2. B.As an in-memory store for caching and sessions✓ Correct
3. C.As a CSS preprocessor for compiling styles
4. D.As a web server for hosting static content

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Q20. What is SQL injection?

1. A.A vulnerability where malicious SQL is inserted into queries✓ Correct
2. B.A database optimization technique for faster lookups
3. C.A JavaScript technique for dynamically building queries
4. D.Injecting CSS styles into SQL query statements

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Q21. What is database sharding?

1. A.Encrypting data for security and privacy compliance
2. B.Compressing tables to reduce disk storage space
3. C.Splitting a database into smaller distributed pieces✓ Correct
4. D.Breaking a database beyond repair permanently

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Q22. What is the difference between horizontal and vertical partitioning?

1. A.Horizontal splits columns; vertical splits rows across servers
2. B.Neither approach has any effect on query performance
3. C.Horizontal splits rows across servers; vertical splits columns✓ Correct
4. D.They are identical in partitioning strategy

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Q23. What is eventual consistency?

1. A.A CSS consistency model for cross-browser rendering
2. B.Data is always immediately consistent everywhere
3. C.All replicas converge to the same value given enough time✓ Correct
4. D.Data is never consistent across any of the replicas

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Q24. What is a database migration?

1. A.A data backup process for disaster recovery planning
2. B.A CSS migration from one framework to another tool
3. C.Version-controlled changes to schema that can be rolled back✓ Correct
4. D.Moving a database to a new physical data center

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Q25. What is the N+1 query problem and how is it solved?

1. A.A JavaScript error caused by off-by-one array access
2. B.A CSS specificity issue with deeply nested selectors
3. C.A mathematical formula for calculating query cost
4. D.N extra queries for related data; solved by eager loading✓ Correct

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Q26. What is a materialized view?

1. A.A database object storing query results physically✓ Correct
2. B.A CSS view for presenting styled HTML content
3. C.A template engine view for generating dynamic pages
4. D.A JavaScript view for rendering reactive UI components

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Q27. What is connection pooling in database management?

1. A.A swimming pool database for aquatic records
2. B.A CSS pooling technique for shared style rule resources
3. C.A JavaScript object pool for reusing DOM element references
4. D.Maintaining reusable connections to avoid per-request overhead✓ Correct

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Q28. What is a write-ahead log (WAL)?

1. A.A CSS log file for tracking style computation results
2. B.A blogging technique for writing web content
3. C.Changes are written to a log before applying to the DB✓ Correct
4. D.A JavaScript console log for outputting debug messages

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Q29. What is database replication?

1. A.A backup tool for creating periodic data archive snapshots
2. B.A version control system for tracking file change history
3. C.Copying and maintaining data across servers for redundancy✓ Correct
4. D.Copying CSS files across multiple project directories

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Q30. What is the difference between optimistic and pessimistic locking?

1. A.They only apply to NoSQL databases not relational ones
2. B.They are identical in concurrency control approach
3. C.Optimistic always locks; pessimistic never locks anything
4. D.Optimistic checks at commit; pessimistic locks immediately✓ Correct

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