SQL and RDBMS MCQ Test

1. What does SQL stand for?

• A. Structured Query Language
• B. Simple Question Language
• C. Sequential Query Logic
• D. System Query Layer

Answer: Structured Query Language

2. What does RDBMS stand for?

• A. Rapid Database Management System
• B. Relational Database Management System
• C. Remote Data Backup Management System
• D. Recorded Data Batch Management System

Answer: Relational Database Management System

3. In a relational database, what is a table also called?

• A. Tuple
• B. Relation
• C. Attribute
• D. Domain

Answer: Relation

4. What is a row in a database table also called?

• A. Attribute
• B. Tuple
• C. Domain
• D. Schema

Answer: Tuple

5. What is a column in a database table also called?

• A. Tuple
• B. Attribute
• C. Record
• D. Index

Answer: Attribute

6. What is the degree of a relation?

• A. The number of rows
• B. The number of columns
• C. The number of indexes
• D. The number of keys

Answer: The number of columns

7. What is the cardinality of a relation?

• A. The number of columns
• B. The number of rows
• C. The number of tables
• D. The number of constraints

Answer: The number of rows

8. Which key uniquely identifies each record in a table?

• A. Foreign key
• B. Primary key
• C. Candidate key
• D. Composite key

Answer: Primary key

9. Can a primary key column contain NULL values?

• A. Yes, always
• B. No, never
• C. Only one NULL
• D. Only in MySQL

Answer: No, never

10. What is a foreign key?

• A. A key from another country
• B. A column that references the primary key of another table
• C. A duplicate primary key
• D. An encrypted key

Answer: A column that references the primary key of another table

11. What is a candidate key?

• A. Any column with data
• B. An attribute or set of attributes that could serve as the primary key
• C. A deleted key
• D. A key that allows NULLs

Answer: An attribute or set of attributes that could serve as the primary key

12. What is a composite key?

• A. A key made of two or more columns
• B. A key that is encrypted
• C. A key in another table
• D. An automatically generated key

Answer: A key made of two or more columns

13. Which SQL category includes CREATE, ALTER and DROP?

• A. DML
• B. DDL
• C. DCL
• D. TCL

Answer: DDL

14. Which SQL category includes SELECT, INSERT, UPDATE and DELETE?

• A. DDL
• B. DML
• C. DCL
• D. TCL

Answer: DML

15. Which SQL category includes GRANT and REVOKE?

• A. DDL
• B. DML
• C. DCL
• D. TCL

Answer: DCL

16. Which SQL category includes COMMIT and ROLLBACK?

• A. DDL
• B. DML
• C. DCL
• D. TCL

Answer: TCL

17. Which SQL command retrieves data from a table?

• A. GET
• B. SELECT
• C. FETCH
• D. READ

Answer: SELECT

18. Which SQL command adds a new row to a table?

• A. ADD
• B. INSERT
• C. CREATE
• D. APPEND

Answer: INSERT

19. Which SQL command modifies existing rows?

• A. MODIFY
• B. UPDATE
• C. CHANGE
• D. ALTER

Answer: UPDATE

20. Which SQL command removes rows from a table but keeps its structure?

• A. DROP
• B. DELETE
• C. REMOVE
• D. ERASE

Answer: DELETE

21. Which SQL command removes an entire table including its structure?

• A. DELETE
• B. DROP
• C. TRUNCATE
• D. CLEAR

Answer: DROP

22. What is the key difference between DELETE and TRUNCATE?

• A. There is none
• B. TRUNCATE removes all rows quickly and cannot use a WHERE clause
• C. DELETE is faster
• D. TRUNCATE deletes the table structure

Answer: TRUNCATE removes all rows quickly and cannot use a WHERE clause

23. Which clause filters rows in a SELECT statement?

• A. FILTER
• B. WHERE
• C. HAVING
• D. ORDER BY

Answer: WHERE

24. Which clause sorts the result of a query?

• A. SORT BY
• B. ORDER BY
• C. GROUP BY
• D. ARRANGE

Answer: ORDER BY

25. Which keyword sorts results in descending order?

• A. DOWN
• B. DESC
• C. REVERSE
• D. BACKWARD

Answer: DESC

26. Which clause groups rows that share a value?

• A. ORDER BY
• B. GROUP BY
• C. PARTITION
• D. CLUSTER

Answer: GROUP BY

27. Which clause filters groups after GROUP BY?

• A. WHERE
• B. HAVING
• C. FILTER
• D. WHEN

Answer: HAVING

28. What is the difference between WHERE and HAVING?

• A. They are identical
• B. WHERE filters rows before grouping; HAVING filters groups after
• C. HAVING is faster
• D. WHERE only works with numbers

Answer: WHERE filters rows before grouping; HAVING filters groups after

29. Which keyword removes duplicate rows from a result?

• A. UNIQUE
• B. DISTINCT
• C. SINGLE
• D. ONLY

Answer: DISTINCT

30. Which aggregate function returns the number of rows?

• A. SUM()
• B. COUNT()
• C. TOTAL()
• D. NUM()

Answer: COUNT()

31. Which aggregate function returns the average of a column?

• A. MEAN()
• B. AVG()
• C. AVERAGE()
• D. MID()

Answer: AVG()

32. Which aggregate function returns the largest value?

• A. TOP()
• B. MAX()
• C. HIGH()
• D. LARGE()

Answer: MAX()

33. Which operator tests whether a value falls within a range?

• A. IN
• B. BETWEEN
• C. LIKE
• D. RANGE

Answer: BETWEEN

34. Which operator performs pattern matching on text?

• A. MATCH
• B. LIKE
• C. SIMILAR
• D. PATTERN

Answer: LIKE

35. In a LIKE pattern, what does the % wildcard match?

• A. Exactly one character
• B. Zero or more characters
• C. Only digits
• D. Only letters

Answer: Zero or more characters

36. In a LIKE pattern, what does the underscore _ match?

• A. Zero or more characters
• B. Exactly one character
• C. A space
• D. A number

Answer: Exactly one character

37. Which operator checks whether a value is in a given list?

• A. BETWEEN
• B. IN
• C. LIKE
• D. EXISTS

Answer: IN

38. How do you test for a NULL value in SQL?

• A. = NULL
• B. IS NULL
• C. == NULL
• D. EQUALS NULL

Answer: IS NULL

39. Which JOIN returns only rows with matching values in both tables?

• A. LEFT JOIN
• B. INNER JOIN
• C. FULL JOIN
• D. CROSS JOIN

Answer: INNER JOIN

40. Which JOIN returns all rows from the left table and matches from the right?

• A. INNER JOIN
• B. LEFT JOIN
• C. RIGHT JOIN
• D. CROSS JOIN

Answer: LEFT JOIN

41. Which JOIN returns the Cartesian product of two tables?

• A. INNER JOIN
• B. CROSS JOIN
• C. SELF JOIN
• D. NATURAL JOIN

Answer: CROSS JOIN

42. What is a self join?

• A. A table joined with itself
• B. A join with no condition
• C. A join of three tables
• D. An automatic join

Answer: A table joined with itself

43. What is a view in SQL?

• A. A physical copy of a table
• B. A virtual table based on the result of a query
• C. A backup file
• D. An index

Answer: A virtual table based on the result of a query

44. What is an index used for in a database?

• A. Storing backups
• B. Speeding up data retrieval
• C. Encrypting data
• D. Compressing tables

Answer: Speeding up data retrieval

45. What is a stored procedure?

• A. A saved query result
• B. A precompiled set of SQL statements stored in the database
• C. A backup routine
• D. A table constraint

Answer: A precompiled set of SQL statements stored in the database

46. What is a trigger in a database?

• A. A manual command
• B. Code that runs automatically in response to a table event
• C. A type of index
• D. A user permission

Answer: Code that runs automatically in response to a table event

47. What does the ACID acronym stand for in transactions?

• A. Atomicity, Consistency, Isolation, Durability
• B. Access, Control, Integrity, Data
• C. Automatic, Correct, Indexed, Distributed
• D. Aggregate, Compute, Insert, Delete

Answer: Atomicity, Consistency, Isolation, Durability

48. Which ACID property ensures a transaction completes fully or not at all?

• A. Consistency
• B. Atomicity
• C. Isolation
• D. Durability

Answer: Atomicity

49. Which ACID property ensures committed changes survive a system failure?

• A. Atomicity
• B. Durability
• C. Isolation
• D. Consistency

Answer: Durability

50. What is normalisation in database design?

• A. Making all data uppercase
• B. Organising data to reduce redundancy and improve integrity
• C. Compressing the database
• D. Backing up tables

Answer: Organising data to reduce redundancy and improve integrity

51. What does First Normal Form (1NF) require?

• A. No partial dependencies
• B. All attribute values must be atomic (indivisible)
• C. No transitive dependencies
• D. Every column must be indexed

Answer: All attribute values must be atomic (indivisible)

52. What does Second Normal Form (2NF) eliminate?

• A. Repeating groups
• B. Partial dependency on part of a composite key
• C. Transitive dependency
• D. Multi-valued dependency

Answer: Partial dependency on part of a composite key

53. What does Third Normal Form (3NF) eliminate?

• A. Partial dependency
• B. Transitive dependency
• C. Atomic values
• D. Foreign keys

Answer: Transitive dependency

54. What is denormalisation?

• A. Removing all data
• B. Deliberately adding redundancy to improve read performance
• C. Deleting a table
• D. Encrypting a database

Answer: Deliberately adding redundancy to improve read performance

55. In an ER diagram, what shape usually represents an entity?

• A. Oval
• B. Rectangle
• C. Diamond
• D. Circle

Answer: Rectangle

56. In an ER diagram, what shape usually represents a relationship?

• A. Rectangle
• B. Diamond
• C. Oval
• D. Triangle

Answer: Diamond

57. In an ER diagram, what shape usually represents an attribute?

• A. Rectangle
• B. Oval
• C. Diamond
• D. Square

Answer: Oval

58. Which SQL statement changes the structure of an existing table?

• A. UPDATE
• B. ALTER TABLE
• C. MODIFY
• D. CHANGE TABLE

Answer: ALTER TABLE

59. Which constraint ensures all values in a column are different?

• A. NOT NULL
• B. UNIQUE
• C. CHECK
• D. DEFAULT

Answer: UNIQUE

60. Which constraint prevents a column from having empty values?

• A. UNIQUE
• B. NOT NULL
• C. PRIMARY KEY
• D. CHECK

Answer: NOT NULL

61. Which constraint validates data against a condition?

• A. CHECK
• B. UNIQUE
• C. DEFAULT
• D. INDEX

Answer: CHECK

62. What is a subquery?

• A. A query inside another query
• B. A short query
• C. A failed query
• D. A saved query

Answer: A query inside another query

63. Which command undoes changes made in the current transaction?

• A. COMMIT
• B. ROLLBACK
• C. UNDO
• D. RESTORE

Answer: ROLLBACK

64. Which command permanently saves transaction changes?

• A. SAVE
• B. COMMIT
• C. WRITE
• D. STORE

Answer: COMMIT

65. Who proposed the relational model of databases?

• A. Charles Babbage
• B. E. F. Codd
• C. Alan Turing
• D. Larry Ellison

Answer: E. F. Codd

66. What is DBMS software responsible for?

• A. Designing websites
• B. Creating, managing and controlling access to databases
• C. Compiling programs
• D. Managing printers

Answer: Creating, managing and controlling access to databases