Relational Database Model MCQs in DBMS

1. In a relational database, a table is also known as a:

(A) Tuple

(B) Relation

(C) Attribute

(D) Schema

2. Which of the following best describes a tuple in a relational database?

(A) A column in a table

(B) A row in a table

(C) A set of tables

(D) A database schema

3. In a relational database, an attribute is:

(A) A row in a table

(B) A column in a table

(C) A set of rows

(D) A table

4. Which term is used to describe the set of all possible values an attribute can have?

(A) Domain

(B) Range

(C) Tuple

(D) Relation

5. A relation in a relational database can be defined as:

(A) A single column in a table

(B) A collection of rows and columns in a table

(C) A unique identifier for a row

(D) A method to retrieve data

6. Which of the following is a key characteristic of a relation (table) in a relational database?

(A) Each row is unique.

(B) Each column has a unique name.

(C) Columns can have different data types.

(D) All of the above.

7. In the context of a relational database, a primary key is:

(A) A unique identifier for each row in a table.

(B) A column that can have duplicate values.

(C) A key used to link two tables.

(D) A non-unique identifier.

8. Which of the following is true about a foreign key in a relational database?

(A) It must be unique within its table.

(B) It is used to link tables together.

(C) It cannot be null.

(D) It is the same as a primary key.

9. The degree of a relation refers to:

(A) The number of rows in the relation.

(B) The number of columns in the relation.

(C) The number of tables in the database.

(D) The number of keys in the relation.

10. The cardinality of a relation refers to:

(A) The number of columns in the relation.

(B) The number of rows in the relation.

(C) The number of relations in the database.

(D) The number of keys in the relation.

11. Which of the following best describes a composite key?

(A) A key that uniquely identifies a row and is composed of multiple columns.

(B) A key that links to a primary key in another table.

(C) A key that can contain null values.

(D) A key that is used for indexing.

12. Which of the following SQL commands is used to create a new table in a database?

(A) INSERT

(B) UPDATE

(C) CREATE TABLE

(D) ALTER TABLE

13. What is the purpose of the NOT NULL constraint in a table column?

(A) To ensure that all values in the column are unique.

(B) To ensure that no two rows have the same value in the column.

(C) To ensure that the column cannot contain null values.

(D) To link the column to another table.

14. Which SQL statement is used to modify an existing table structure, such as adding a new column?

(A) CREATE TABLE

(B) ALTER TABLE

(C) DROP TABLE

(D) SELECT

15. In a relational database, the term “schema” refers to:

(A) The structure of the database, including tables, columns, and relationships.

(B) A single table in the database.

(C) A specific row in a table.

(D) The data type of a column.

16. Which of the following is an example of an attribute in a student database table?

(A) StudentID

(B) Students

(C) Enrollment

(D) Database

17. Which SQL keyword is used to retrieve data from a database table?

(A) SELECT

(B) UPDATE

(C) DELETE

(D) INSERT

18. Which of the following best describes the term “relation” in the context of a relational database?

(A) A method for querying data.

(B) A mathematical concept represented by a table.

(C) A unique identifier for a row.

(D) A column in a table.

19. Which SQL command is used to remove a table from a database?

(A) DELETE TABLE

(B) REMOVE TABLE

(C) DROP TABLE

(D) ALTER TABLE

20. In a relational database, a candidate key is:

(A) A key that can uniquely identify a row but is not chosen as the primary key.

(B) A key that cannot contain null values.

(C) A key that is composed of multiple columns.

(D) A key that links two tables together.