Database System MCQs

1. What is a database?

A) A collection of related data
B) A type of software application
C) A programming language
D) A hardware device

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2. What does DBMS stand for?

A) Database Management System
B) Data Binary Management System
C) Database Master System
D) Data Management Software

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3. Which of the following is a type of DBMS?

A) Hierarchical
B) Relational
C) Object-oriented
D) All of the above

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4. What is SQL?

A) Structured Query Language
B) Simple Query Language
C) Standard Query Language
D) Sequential Query Language

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5. What is a primary key?

A) A unique identifier for a record in a table
B) A foreign key that links two tables
C) A column that allows null values
D) A field that stores text data

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6. What is a foreign key?

A) A key used to link two tables together
B) A unique identifier for a record
C) A primary key from another table
D) Both A and C

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7. What is normalization?

A) The process of organizing data to reduce redundancy
B) The process of creating backups
C) The process of indexing a database
D) The process of encrypting data

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8. What is a transaction?

A) A sequence of operations performed as a single logical unit
B) A data retrieval operation
C) A method of sorting data
D) A way to store data

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9. What does ACID stand for in database systems?

A) Atomicity, Consistency, Isolation, Durability
B) Atomicity, Concurrency, Isolation, Durability
C) Availability, Consistency, Isolation, Durability
D) Atomicity, Consistency, Integrity, Durability

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10. What is a schema in a database?

A) The structure that defines the organization of data
B) A query written in SQL
C) A data backup
D) A type of relationship between tables

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11. What is a data model?

A) A conceptual representation of data structures
B) A physical representation of a database
C) A database management tool
D) A programming language for databases

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12. Which of the following is NOT a SQL command?

A) SELECT
B) GET
C) INSERT
D) UPDATE

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13. What is an index in a database?

A) A data structure that improves the speed of data retrieval
B) A type of backup
C) A method for normalizing data
D) A record in a table

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14. What does a Data Dictionary contain?

A) Metadata about the database structure
B) User data
C) Backup information
D) Security settings

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15. What is a join in SQL?

A) A method for combining rows from two or more tables
B) A way to create a new table
C) A type of data model
D) A method for deleting records

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16. What type of join returns all records from both tables?

A) Inner Join
B) Outer Join
C) Cross Join
D) Self Join

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17. What is a view in SQL?

A) A virtual table based on the result of a SELECT query
B) A permanent table in the database
C) A backup of the database
D) A method for securing data

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18. What does the GROUP BY clause do in SQL?

A) It groups rows that have the same values in specified columns
B) It orders the results of a query
C) It filters records based on conditions
D) It joins multiple tables together

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19. What is the purpose of the WHERE clause in SQL?

A) To filter records based on specific conditions
B) To group records
C) To sort records
D) To create a view

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20. What does the term “denormalization” mean?

A) The process of combining tables to reduce the number of joins
B) The process of removing redundant data
C) The process of restoring a database
D) The process of encrypting data

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21. What is a stored procedure?

A) A set of SQL statements that can be executed as a single command
B) A backup of the database
C) A data retrieval operation
D) A method for normalizing data

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22. What is a trigger in a database?

A) A set of instructions that automatically executes in response to certain events
B) A method for backing up data
C) A type of database query
D) A record in a table

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23. What does OLAP stand for?

A) Online Analytical Processing
B) Online Application Processing
C) Offline Analytical Processing
D) Online Access Programming

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24. What is the purpose of a data warehouse?

A) To store large volumes of data for analysis
B) To execute transactions quickly
C) To provide real-time data access
D) To maintain operational databases

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25. What is a column in a database table?

A) A vertical entity in a table that represents a specific attribute
B) A horizontal entity in a table that represents a record
C) A type of database query
D) A method for sorting data

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26. What is a row in a database table?

A) A horizontal entity in a table that represents a single record
B) A vertical entity in a table that represents an attribute
C) A type of database query
D) A method for filtering data

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27. What does the term “referential integrity” mean?

A) Ensuring that relationships between tables remain consistent
B) Ensuring that all data is backed up
C) Ensuring that all queries are optimized
D) Ensuring that data is normalized

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28. What is a composite key?

A) A key that consists of two or more attributes
B) A unique identifier for a table
C) A foreign key from another table
D) A type of index

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29. What is the purpose of a database backup?

A) To create a copy of data for recovery purposes
B) To delete unnecessary records
C) To optimize query performance
D) To improve data security

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30. What is a deadlock in database systems?

A) A situation where two or more transactions are unable to proceed because each is waiting for the other to release resources
B) A method for optimizing queries
C) A type of data anomaly
D) A technique for indexing data

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31. What is the purpose of indexing in a database?

A) To improve the speed of data retrieval operations
B) To ensure data integrity
C) To store backup copies of data
D) To normalize data

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32. What does the term “data integrity” refer to?

A) The accuracy and consistency of data in a database
B) The speed of data retrieval
C) The amount of data stored
D) The complexity of database queries

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33. What is an entity-relationship (ER) model?

A) A diagram that represents the entities and their relationships in a database
B) A type of SQL query
C) A method for indexing data
D) A technique for normalizing data

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34. What is a flat-file database?

A) A database that stores data in a single table without relationships
B) A relational database
C) A NoSQL database
D) A type of cloud database

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35. What is the purpose of a database administrator (DBA)?

A) To manage and maintain database systems
B) To design application software
C) To perform data analysis
D) To create backup copies of data

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36. What does the term “data mining” refer to?

A) The process of discovering patterns and knowledge from large amounts of data
B) The process of backing up data
C) The process of normalizing data
D) The process of deleting unnecessary records

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37. What is a NoSQL database?

A) A database that uses a non-relational data model
B) A database that does not require a schema
C) A database designed for distributed data storage
D) All of the above

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38. What is a surrogate key?

A) A unique identifier for an entity that is not derived from application data
B) A primary key derived from another table
C) A key that allows null values
D) A foreign key that refers to a non-primary key

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39. What does the term “sharding” refer to in database systems?

A) The process of splitting a database into smaller, more manageable pieces
B) The process of backing up data
C) The process of indexing data
D) The process of creating a data model

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40. What is a data lake?

A) A centralized repository for storing large amounts of structured and unstructured data
B) A type of relational database
C) A method for normalizing data
D) A backup solution for databases

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41. What is a materialized view?

A) A view that stores the result of a query physically
B) A virtual table that does not store data
C) A type of SQL function
D) A backup of the database

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42. What is a schema in the context of a database?

A) The structure that defines the organization of data
B) A SQL command
C) A type of backup
D) A type of index

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43. What is a data type?

A) A classification of data that specifies the type of value it can hold
B) A method for indexing data
C) A command in SQL
D) A type of database query

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44. What does the term “data redundancy” refer to?

A) The unnecessary duplication of data in a database
B) The process of backing up data
C) The creation of multiple copies of the same data
D) A method for optimizing queries

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45. What is a data warehouse?

A) A central repository for data that is used for reporting and data analysis
B) A type of operational database
C) A method for storing backup data
D) A type of NoSQL database

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46. What is a data model?

A) A conceptual representation of the data structures
B) A type of database management system
C) A method for optimizing queries
D) A programming language for databases

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47. What is a database transaction?

A) A sequence of operations performed as a single logical unit of work
B) A method for optimizing queries
C) A backup of data
D) A method for retrieving data

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48. What is the purpose of a rollback in database systems?

A) To revert the database to a previous state in case of an error
B) To optimize queries
C) To create backups
D) To delete unnecessary records

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49. What does the term “concurrency control” refer to?

A) The management of simultaneous operations on a database without conflicts
B) The process of backing up data
C) The process of normalizing data
D) The process of indexing data

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50. What is an aggregate function in SQL?

A) A function that performs a calculation on a set of values and returns a single value
B) A function that retrieves data from a table
C) A function that creates a new table
D) A function that deletes records from a table

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51. What does the SQL command DELETE do?

A) It removes records from a table
B) It updates records in a table
C) It retrieves records from a table
D) It creates a new table

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52. What is a database cursor?

A) A database object that allows for row-by-row processing of the result set
B) A method for deleting records
C) A type of backup
D) A command in SQL

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53. What is the purpose of the HAVING clause in SQL?

A) To filter records after grouping them
B) To sort records
C) To join tables
D) To create a view

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54. What is an outer join?

A) A join that returns all records from one table and matched records from another table
B) A join that returns records only if there is a match
C) A join that combines all records from both tables
D) A join that filters records based on conditions

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55. What is a logical data model?

A) A representation of data that focuses on the organization and relationships
B) A physical representation of data storage
C) A backup strategy for data
D) A method for indexing data

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56. What does the term “data governance” refer to?

A) The management of data availability, usability, integrity, and security
B) The process of data retrieval
C) The technique of data backup
D) The process of data analysis

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57. What is the purpose of the SELECT statement in SQL?

A) To retrieve data from a database
B) To create a new table
C) To update records in a table
D) To delete records from a table

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58. What is a nested query in SQL?

A) A query within another query
B) A type of join
C) A method for sorting data
D) A backup strategy

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59. What is an XML database?

A) A database that stores data in XML format
B) A relational database
C) A type of NoSQL database
D) A backup solution for databases

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60. What is a distributed database?

A) A database that is spread across multiple locations or servers
B) A database that is stored on a single server
C) A type of backup
D) A type of relational database

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61. What is a JSON database?

A) A database that uses JSON (JavaScript Object Notation) to store data
B) A relational database
C) A type of NoSQL database
D) A backup solution for databases

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62. What is the difference between a clustered index and a non-clustered index?

A) A clustered index determines the physical order of data, while a non-clustered index does not
B) A non-clustered index stores data physically, while a clustered index does not
C) A clustered index allows duplicate values, while a non-clustered index does not
D) There is no difference; both are the same

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63. What is a relational database?

A) A database that organizes data into tables with relationships between them
B) A database that stores data as key-value pairs
C) A database that does not use any structure
D) A database that is based on object-oriented programming

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64. What does the term “data abstraction” refer to?

A) The separation of the user interface from the data storage
B) The process of normalizing data
C) The creation of backups
D) The design of the user interface

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65. What is the purpose of the INSERT statement in SQL?

A) To add new records to a table
B) To delete records from a table
C) To update existing records
D) To create a new table

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66. What is a column constraint in SQL?

A) A rule that defines the properties of a column in a table
B) A method for optimizing queries
C) A type of backup
D) A command to create a table

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67. What is a composite entity?

A) An entity that is used to represent a many-to-many relationship
B) An entity that has a single attribute
C) An entity that has no attributes
D) An entity that stores backup data

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68. What is a default value in a database?

A) A value that is automatically assigned to a column if no value is provided
B) A value that cannot be changed
C) A value that must be unique
D) A value that is always null

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69. What is a normalization form?

A) A set of rules for organizing data in a relational database
B) A type of database query
C) A method for creating backups
D) A command in SQL

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70. What does the term “data consistency” refer to?

A) Ensuring that data is accurate and reliable across the database
B) Ensuring that data is available at all times
C) Ensuring that data is backed up regularly
D) Ensuring that data is normalized

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71. What is a database migration?

A) The process of moving data from one database to another
B) The process of creating a backup
C) The process of optimizing queries
D) The process of normalizing data

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72. What is a data access layer?

A) A layer that provides a way to access data in a database
B) A method for indexing data
C) A command in SQL
D) A type of database query

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73. What is a database cluster?

A) A group of servers that work together to store and manage data
B) A method for indexing data
C) A type of database query
D) A backup strategy

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74. What is a database partitioning?

A) The process of dividing a database into smaller, more manageable pieces
B) The process of backing up data
C) The process of indexing data
D) The process of restoring data

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75. What is the purpose of the ORDER BY clause in SQL?

A) To sort the result set of a query
B) To filter records
C) To join tables
D) To create a view

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76. What is a data mart?

A) A subset of a data warehouse focused on a specific business line or team
B) A type of operational database
C) A method for backing up data
D) A type of NoSQL database

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77. What is the purpose of a database trigger?

A) To automatically execute a predefined action in response to certain events
B) To create a new table
C) To update records
D) To delete records

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78. What does the term “eventual consistency” refer to?

A) A model of data consistency where updates may not be immediately visible
B) A type of database query
C) A method for backing up data
D) A process of normalizing data

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79. What is a transaction log?

A) A record of all transactions performed on a database
B) A backup of the database
C) A method for indexing data
D) A command in SQL

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80. What is a database management system (DBMS)?

A) Software that interacts with the user, applications, and the database to capture and analyze data
B) A type of data model
C) A programming language for databases
D) A method for indexing data

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81. What is the purpose of the RDBMS?

A) To manage relational databases
B) To store unstructured data
C) To create backups of databases
D) To optimize queries

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82. What is a hierarchical database model?

A) A database model that organizes data in a tree-like structure
B) A model that organizes data in tables
C) A model that stores data as key-value pairs
D) A model that is used for unstructured data

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83. What is a key-value store?

A) A type of NoSQL database that uses a simple key-value method to store data
B) A relational database
C) A backup solution for databases
D) A method for normalizing data

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84. What is the purpose of data redundancy elimination?

A) To remove duplicate data and ensure efficiency
B) To back up data
C) To optimize queries
D) To create a new table

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85. What is an object-oriented database?

A) A database that represents data in the form of objects
B) A relational database
C) A flat-file database
D) A type of NoSQL database

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86. What does the term “data visualization” refer to?

A) The representation of data in graphical formats to gain insights
B) The process of backing up data
C) The creation of a data model
D) The execution of SQL queries

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87. What is the purpose of data replication?

A) To copy data from one database to another for redundancy and availability
B) To back up data
C) To delete unnecessary records
D) To optimize queries

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88. What is the SQL command UPDATE used for?

A) To modify existing records in a table
B) To create a new table
C) To delete records from a table
D) To retrieve records from a table

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89. What is a dimension table in a data warehouse?

A) A table that stores descriptive attributes related to facts
B) A table that stores transactional data
C) A table that contains foreign keys
D) A backup of the database

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90. What is a fact table in a data warehouse?

A) A table that contains measurable, quantitative data
B) A table that stores metadata
C) A table that contains descriptive attributes
D) A backup of the database

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91. What is the purpose of a data pipeline?

A) To facilitate the movement and processing of data from one system to another
B) To back up data
C) To create a new table
D) To optimize queries

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92. What is the purpose of data cleansing?

A) To improve the quality of data by removing inaccuracies and inconsistencies
B) To create backups
C) To delete unnecessary records
D) To optimize queries

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93. What does the term “data archiving” refer to?

A) The process of moving data that is no longer actively used to a separate storage for long-term retention
B) The process of backing up data
C) The process of indexing data
D) The process of restoring data

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94. What is a database instance?

A) A specific implementation of a database
B) A backup of the database
C) A type of query
D) A method for indexing data

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95. What does the term “load balancing” refer to in databases?

A) The distribution of workload across multiple servers to ensure reliability and performance
B) The process of backing up data
C) The method of normalizing data
D) The creation of indexes

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96. What is a data scientist?

A) A professional who uses statistical and computational techniques to analyze and interpret complex data
B) A database administrator
C) A software developer
D) A system architect

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97. What is a business intelligence (BI) system?

A) A system that helps organizations analyze data to make informed business decisions
B) A database management system
C) A programming language
D) A type of NoSQL database

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98. What does the term “data integrity constraint” refer to?

A) Rules that ensure data accuracy and reliability in a database
B) The process of backing up data
C) The method for normalizing data
D) The creation of a new table

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99. What is a data flow diagram?

A) A visual representation of the flow of data in a system
B) A type of database query
C) A method for indexing data
D) A backup solution for databases

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100. What is an ETL process?

A) Extract, Transform, Load – a process for moving and transforming data
B) Extract, Transfer, Load – a process for backing up data
C) Extract, Test, Load – a process for validating data
D) Extract, Translate, Load – a process for converting data formats

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101. What is a composite key?

A) A key that consists of two or more attributes
B) A key that is created automatically
C) A key that is not unique
D) A key that is generated by a trigger

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102. What is SQL injection?

A) A technique used to attack databases by injecting malicious SQL statements
B) A method for optimizing SQL queries
C) A process of backing up data
D) A type of database normalization

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103. What does the term “foreign key” refer to?

A) A field that links two tables together
B) A unique identifier for a record
C) A key that cannot be null
D) A field that contains duplicate values

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104. What is the purpose of indexing in a database?

A) To speed up the retrieval of records
B) To ensure data integrity
C) To create backups
D) To normalize data

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105. What is a relational database?

A) A database that stores data in tables with relationships
B) A database that uses key-value pairs
C) A flat-file database
D) A database that stores unstructured data

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106. What is the purpose of the WHERE clause in SQL?

A) To filter records based on a specified condition
B) To join tables together
C) To create new records
D) To delete records from a table

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107. What is a stored procedure?

A) A set of SQL statements that can be stored and executed on demand
B) A method for creating backups
C) A way to optimize queries
D) A type of database trigger

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108. What does the term “data warehouse” refer to?

A) A centralized repository for storing large amounts of data for analysis
B) A type of operational database
C) A method for backing up data
D) A data normalization technique

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109. What is the purpose of a primary key?

A) To uniquely identify each record in a table
B) To establish a relationship between two tables
C) To store duplicate values
D) To provide a method for indexing

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110. What is a SQL view?

A) A virtual table created based on the result of a query
B) A physical table in the database
C) A method for backing up data
D) A type of database trigger

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111. What does ACID stand for in database systems?

A) Atomicity, Consistency, Isolation, Durability
B) Access, Control, Integrity, Data
C) Aggregate, Combine, Index, Delete
D) Automated, Command, Interface, Data

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112. What is the role of a database administrator (DBA)?

A) To manage and maintain the database system
B) To write application code
C) To perform data analysis
D) To design user interfaces

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113. What is denormalization in a database?

A) The process of adding redundancy to improve performance
B) The process of removing duplicate records
C) The process of dividing a database into smaller tables
D) The process of backing up data

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114. What is a surrogate key?

A) A unique identifier that is generated when no natural key is available
B) A foreign key in a different table
C) A key that is derived from an existing key
D) A key that allows duplicate values

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115. What does the term “data governance” refer to?

A) The management of data availability, usability, integrity, and security
B) The process of normalizing data
C) The method for backing up data
D) The creation of indexes

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116. What is a column family in NoSQL databases?

A) A set of rows that share the same attributes
B) A table that contains all the records
C) A backup of the database
D) A method for indexing data

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117. What is a database schema?

A) The structure that defines the organization of data in a database
B) The method for optimizing queries
C) The process of creating backups
D) The command to retrieve data

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118. What is a relational model?

A) A way of structuring data using tables and relationships
B) A method for storing unstructured data
C) A way to represent data as objects
D) A method for optimizing queries

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119. What is an aggregate function in SQL?

A) A function that performs a calculation on a set of values and returns a single value
B) A function that retrieves data from multiple tables
C) A function that modifies records
D) A function that creates a new table

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120. What is the purpose of the GROUP BY clause in SQL?

A) To group rows that have the same values in specified columns
B) To filter records
C) To join tables together
D) To sort the results of a query

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121. What is a database connection pool?

A) A cache of database connections that can be reused
B) A method for optimizing queries
C) A process of backing up data
D) A type of NoSQL database

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122. What does the term “data lineage” refer to?

A) The history of data, including its origin and transformations
B) The method for indexing data
C) The process of creating backups
D) The command to retrieve data

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123. What is a data dictionary?

A) A collection of metadata that describes the structure of the database
B) A backup of the database
C) A method for normalizing data
D) A type of SQL command

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124. What is a multi-model database?

A) A database that supports multiple data models, such as relational, document, and graph
B) A traditional relational database
C) A flat-file database
D) A method for backing up data

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125. What is data encryption in databases?

A) The process of converting data into a code to prevent unauthorized access
B) The method for backing up data
C) The process of indexing data
D) The process of restoring data

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126. What is the purpose of a database transaction?

A) To ensure that a series of operations are completed successfully or not at all
B) To create new records
C) To delete records from a table
D) To optimize queries

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127. What is an OLAP system?

A) Online Analytical Processing – a system for analyzing complex data
B) Online Local Access Protocol – a database access protocol
C) Offline Language Access Protocol – a method for data storage
D) Online Language Analytical Processing – a data processing technique

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128. What does the term “horizontal scaling” refer to in databases?

A) Adding more machines to handle increased load
B) Upgrading existing hardware to improve performance
C) Decreasing the size of the database
D) Consolidating multiple databases into one

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129. What is a document database?

A) A NoSQL database that stores data in documents rather than rows and columns
B) A traditional relational database
C) A flat-file database
D) A method for backing up data

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130. What is the purpose of a database cache?

A) To temporarily store frequently accessed data for faster retrieval
B) To create backups
C) To optimize queries
D) To delete unnecessary records

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