Here are 50 MCQs on Database Management Systems (DBMS):
1. Which of the following is a database model?
- A) Relational Model
- B) Object-Oriented Model
- C) Hierarchical Model
- D) All of the above
Answer: D) All of the above
There are several types of database models: Relational, Object-Oriented, and Hierarchical are common models used in DBMS.
2. Which of the following is a DBMS software?
- A) MySQL
- B) Oracle
- C) Microsoft SQL Server
- D) All of the above
Answer: D) All of the above
MySQL, Oracle, and Microsoft SQL Server are all examples of popular DBMS software used to manage databases.
3. What does SQL stand for?
- A) Standard Query Language
- B) Structured Query Language
- C) Simple Query Language
- D) Structured Question Language
Answer: B) Structured Query Language
SQL is a language designed for managing and querying data in a relational database.
4. What is the primary key used for in a database?
- A) Uniquely identify each record
- B) Group records together
- C) Store data
- D) Link multiple tables
Answer: A) Uniquely identify each record
A primary key ensures that each record in a table is unique and can be identified.
5. What is a foreign key in a database?
- A) A key that is used to link tables
- B) A key that uniquely identifies records
- C) A type of primary key
- D) A non-unique key
Answer: A) A key that is used to link tables
A foreign key is used to establish a relationship between two tables by referring to the primary key of another table.
6. Which of the following is NOT a type of database?
- A) Relational Database
- B) Object-Oriented Database
- C) Document Database
- D) Network Database
Answer: D) Network Database
The Network Database is a model used in DBMS, but it is not considered a “type” in the context of popular DBMS types like relational or document.
7. Which command is used to delete a table in SQL?
- A) DELETE TABLE
- B) REMOVE TABLE
- C) DROP TABLE
- D) TRUNCATE TABLE
Answer: C) DROP TABLE
The DROP TABLE command is used to delete a table from the database entirely.
8. What is normalization in DBMS?
- A) A method to reduce redundancy
- B) A way of improving data integrity
- C) A way to break down large tables into smaller ones
- D) All of the above
Answer: D) All of the above
Normalization aims to organize data efficiently by minimizing redundancy and improving data integrity.
9. Which of the following is a characteristic of a relational database?
- A) Data is stored in tables
- B) Tables can have multiple relationships
- C) Data is organized using primary and foreign keys
- D) All of the above
Answer: D) All of the above
Relational databases use tables to organize data and relationships among them, with primary and foreign keys linking records.
10. What does a database schema define?
- A) The structure of the database
- B) The database user permissions
- C) The data types of each column
- D) The relationships between tables
Answer: A) The structure of the database
A database schema defines how data is organized within the database, including tables, views, indexes, and relationships.
11. What is an index in a DBMS?
- A) A collection of pointers used to speed up searches
- B) A type of data structure
- C) A method to enforce data integrity
- D) A command for sorting data
Answer: A) A collection of pointers used to speed up searches
An index is used to improve the speed of data retrieval operations by maintaining a collection of pointers to records.
12. What is a relationship in DBMS?
- A) A logical connection between tables
- B) A connection between users
- C) A physical connection between files
- D) A connection between rows and columns
Answer: A) A logical connection between tables
A relationship in a DBMS refers to how data in one table is related to data in another table.
13. Which type of relationship exists between the “Customers” and “Orders” tables in a typical e-commerce database?
- A) One-to-One
- B) One-to-Many
- C) Many-to-Many
- D) Many-to-One
Answer: B) One-to-Many
A customer can place many orders, but each order is placed by one customer, making it a one-to-many relationship.
14. What does the SQL SELECT statement do?
- A) Modifies data in a database
- B) Deletes records from a database
- C) Retrieves data from a database
- D) Creates a new table
Answer: C) Retrieves data from a database
The SELECT statement is used to query and retrieve data from one or more tables.
15. What is a view in a DBMS?
- A) A stored procedure
- B) A virtual table created from the results of a query
- C) A physical copy of a table
- D) A backup of a database
Answer: B) A virtual table created from the results of a query
A view is a virtual table that contains the results of a SELECT query.
16. Which of the following is an example of a constraint in a DBMS?
- A) NOT NULL
- B) UNIQUE
- C) FOREIGN KEY
- D) All of the above
Answer: D) All of the above
NOT NULL, UNIQUE, and FOREIGN KEY are all types of constraints used to enforce data integrity.
17. What is the use of the SQL UPDATE statement?
- A) To modify the values of existing records
- B) To delete records
- C) To create new records
- D) To query data
Answer: A) To modify the values of existing records
The UPDATE statement is used to modify the existing data in a table.
18. What is the purpose of the SQL INSERT statement?
- A) To delete data from a table
- B) To insert data into a table
- C) To modify data in a table
- D) To select data from a table
Answer: B) To insert data into a table
The INSERT INTO statement is used to add new rows of data into a table.
19. Which of the following is a feature of DBMS?
- A) Data security
- B) Data redundancy
- C) Inability to handle large volumes of data
- D) No data integrity
Answer: A) Data security
A DBMS provides various features, including data security, to protect data from unauthorized access.
20. What is the role of a database administrator (DBA)?
- A) Managing and securing database systems
- B) Writing SQL queries
- C) Developing database models
- D) All of the above
Answer: D) All of the above
A DBA is responsible for managing, securing, and overseeing the performance of database systems, writing SQL queries, and database design.
21. In DBMS, what is a table?
- A) A collection of rows and columns
- B) A type of relationship
- C) A data manipulation operation
- D) A software application used to manage data
Answer: A) A collection of rows and columns
In DBMS, a table is used to store data in rows and columns.
22. What is the difference between DELETE and TRUNCATE in SQL?
- A) DELETE removes records one by one, while TRUNCATE removes all records quickly
- B) DELETE removes all records, while TRUNCATE removes one record
- C) TRUNCATE is used to delete a table
- D) There is no difference
Answer: A) DELETE removes records one by one, while TRUNCATE removes all records quickly
DELETE is slower as it removes rows one by one and logs each deletion, while TRUNCATE is faster and doesn’t log individual row deletions.
23. Which of the following is a type of join in SQL?
- A) INNER JOIN
- B) LEFT JOIN
- C) RIGHT JOIN
- D) All of the above
Answer: D) All of the above
INNER JOIN, LEFT JOIN, and RIGHT JOIN are all types of joins used to combine data from multiple tables.
24. What is the ACID property in DBMS?
- A) Atomicity, Consistency, Isolation, Durability
- B) Accuracy, Consistency, Integrity, Durability
- C) Atomicity, Completeness, Isolation, Durability
- D) None of the above
Answer: A) Atomicity, Consistency, Isolation, Durability
ACID is a set of properties that ensure database transactions are processed reliably.
25. What is denormalization in DBMS?
- A) The process of organizing data to minimize redundancy
- B) The process of introducing redundancy into a database for performance optimization
- C) The process of creating indexes
- D) The process of deleting unnecessary records
Answer: B) The process of introducing redundancy into a database for performance optimization
Denormalization is done to improve performance by reducing the complexity of queries.
26. What is a stored procedure in DBMS?
- A) A set of SQL queries stored in the database
- B) A method to generate reports
- C) A tool for data visualization
- D) A backup process
Answer: A) A set of SQL queries stored in the database
A stored procedure is a precompiled collection of SQL statements stored in the database, designed to perform specific tasks.
27. Which of the following is true about a primary key?
- A) It can have duplicate values
- B) It must have unique values
- C) It can be NULL
- D) It can be a foreign key
Answer: B) It must have unique values
A primary key must contain unique values and cannot be NULL.
28. What is the difference between UNION and UNION ALL in SQL?
- A) UNION removes duplicate values, while UNION ALL includes duplicates
- B) UNION is faster than UNION ALL
- C) UNION ALL removes duplicates
- D) There is no difference
Answer: A) UNION removes duplicate values, while UNION ALL includes duplicates
UNION combines results from multiple queries, removing duplicates, while UNION ALL includes all results, even duplicates.
29. What is the function of the SQL GROUP BY clause?
- A) It orders the results in ascending order
- B) It filters the results based on conditions
- C) It groups rows that have the same values in specified columns
- D) It joins multiple tables
Answer: C) It groups rows that have the same values in specified columns
GROUP BY is used to group rows based on one or more columns.
30. What is a subquery in SQL?
- A) A query embedded inside another query
- B) A function that generates results
- C) A query that performs a join
- D) A command used to delete data
Answer: A) A query embedded inside another query
A subquery is a query nested inside another SQL query to perform more complex operations.
31. What is an entity in DBMS?
- A) A set of attributes
- B) A physical database object
- C) A collection of related data
- D) An object that can have attributes
Answer: D) An object that can have attributes
An entity in a database is an object or concept that has attributes (properties).
32. What is a trigger in DBMS?
- A) A function that is executed automatically in response to an event
- B) A type of query
- C) A user command
- D) A mechanism for indexing
Answer: A) A function that is executed automatically in response to an event
A trigger is a database object that automatically executes or fires when certain events occur.
33. Which of the following is used to enforce data integrity in DBMS?
- A) Constraints
- B) Normalization
- C) Indexes
- D) Views
Answer: A) Constraints
Constraints such as NOT NULL, UNIQUE, and FOREIGN KEY enforce data integrity in the database.
34. What does the SQL COUNT() function do?
- A) Counts the number of rows in a table
- B) Counts the number of columns in a table
- C) Counts the number of distinct values in a column
- D) Both A and C
Answer: D) Both A and C
COUNT() counts the number of rows or distinct values in a column.
35. What is a data warehouse in DBMS?
- A) A large collection of raw data
- B) A database designed to handle a large number of transactions
- C) A type of database that stores historical data for analysis
- D) A type of file system
Answer: C) A type of database that stores historical data for analysis
A data warehouse stores large volumes of historical data for analysis and reporting.
36. What is the purpose of normalization?
- A) To remove redundant data
- B) To improve data security
- C) To simplify SQL queries
- D) To delete unused data
Answer: A) To remove redundant data
Normalization is used to minimize data redundancy and improve data integrity in relational databases.
37. What is a relational schema in DBMS?
- A) A diagram that shows the relationships between tables
- B) A set of rules for writing queries
- C) A physical copy of a database
- D) A set of related tables with keys and relationships
Answer: D) A set of related tables with keys and relationships
A relational schema defines the structure of a relational database including tables, keys, and relationships.
38. What is the function of the SQL HAVING clause?
- A) To specify conditions on rows
- B) To specify conditions on groups
- C) To sort the results
- D) To limit the number of results
Answer: B) To specify conditions on groups
HAVING is used to filter groups based on conditions after the GROUP BY clause.
39. Which of the following is NOT a property of a transaction in DBMS?
- A) Atomicity
- B) Consistency
- C) Isolation
- D) Persistence
Answer: D) Persistence
The correct properties are Atomicity, Consistency, Isolation, and Durability (ACID).
40. What is a data model?
- A) A collection of data
- B) A diagrammatic representation of data and relationships
- C) A type of query
- D) A type of storage system
Answer: B) A diagrammatic representation of data and relationships
A data model represents the structure and relationships of data elements in a system.
41. Which SQL statement is used to retrieve all columns from the “employees” table?
- A) SELECT * FROM employees;
- B) SELECT employees FROM *;
- C) GET * FROM employees;
- D) RETRIEVE * FROM employees;
Answer: A) SELECT * FROM employees;
This SQL query retrieves all columns from the “employees” table.
42. What is the purpose of the SQL DISTINCT keyword?
- A) To remove duplicate rows from the result set
- B) To select a distinct table
- C) To create a unique table
- D) To delete duplicate data
Answer: A) To remove duplicate rows from the result set
DISTINCT is used to ensure that the query results contain only unique rows.
43. Which of the following is true about a surrogate key?
- A) It is a system-generated key
- B) It is the same as the primary key
- C) It contains business logic
- D) It can be NULL
Answer: A) It is a system-generated key
A surrogate key is a unique identifier generated by the system, often used when natural keys are not suitable.
44. What does SQL DDL stand for?
- A) Data Definition Language
- B) Data Description Language
- C) Data Dependency Language
- D) Data Domain Language
Answer: A) Data Definition Language
DDL includes SQL commands that define database structures, such as CREATE, ALTER, and DROP.
45. What is a relationship set in DBMS?
- A) A group of entities of the same type
- B) A set of relationships of the same type
- C) A set of keys
- D) A set of primary and foreign keys
Answer: B) A set of relationships of the same type
A relationship set is a collection of relationships between entities in the database.
46. Which of the following is NOT a normal form?
- A) First Normal Form (1NF)
- B) Second Normal Form (2NF)
- C) Third Normal Form (3NF)
- D) Fourth Normal Form (4NF)
Answer: D) Fourth Normal Form (4NF)
There is a Fourth Normal Form (4NF), but it is not listed in standard textbooks as frequently as 1NF, 2NF, and 3NF.
47. What is an Entity-Relationship Diagram (ERD)?
- A) A diagram showing database schema
- B) A diagram for defining relationships between entities
- C) A query optimization tool
- D) A programming language for DBMS
Answer: B) A diagram for defining relationships between entities
An ERD is used to visually represent the structure of a database and relationships between entities.
48. Which of the following can be used to create an index in SQL?
- A) CREATE INDEX
- B) ALTER INDEX
- C) DROP INDEX
- D) SELECT INDEX
Answer: A) CREATE INDEX
The CREATE INDEX statement is used to create an index on a table to speed up query processing.
49. What is a rollback in DBMS?
- A) A command that undoes changes in a transaction
- B) A command to apply changes to the database
- C) A way to view changes in the database
- D) A way to delete a database
Answer: A) A command that undoes changes in a transaction
A rollback undoes any changes made in the current transaction.
50. What is the main benefit of using a DBMS?
- A) Data redundancy
- B) Improved data integrity
- C) Inability to handle complex queries
- D) Difficult data management
Answer: B) Improved data integrity
A DBMS helps maintain data integrity by managing data consistency and preventing redundancy.
These questions should provide a comprehensive overview of DBMS concepts.
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Sidhant Singh is a highly accomplished professional educator with a diverse academic background. He holds a Master’s degree in History, an MSc in Electrical Engineering and a PhD, demonstrating his extensive knowledge and expertise in both the humanities and the sciences. His unique combination of skills enables him to offer a well-rounded perspective in his teaching and research, making him a valuable resource for students across various fields.