Database Concepts Quiz

What is the purpose of normalizing relations in databases?

• To reduce data redundancy and improve data integrity

• To increase data redundancy and improve data integrity

• To reduce the speed of database queries

• To increase the complexity of database design

Answer explanation

Normalizing relations in databases helps reduce data redundancy and improve data integrity by organizing data into separate tables and linking them through relationships.

Why are databases normalised?

• To make them less efficient

• To compromise the integrity of their data

• To ensure that entities contain no redundant or repeated data

• To make them larger and more complex

Answer explanation

Databases are normalised to ensure that entities contain no redundant or repeated data, improving data integrity and efficiency.

What is the benefit of a normalised database over an unnormalised database?

• Slower searching and sorting

• Larger tables

• Faster searching and sorting

• Increased duplication of data

Answer explanation

A normalised database reduces data redundancy by breaking down tables into smaller, related tables, leading to faster searching and sorting due to reduced duplication.

What is minimised in a normalised database?

• Data consistency

• Duplication of data

• Efficiency

• Searching speed

Answer explanation

In a normalised database, duplication of data is minimised to improve data integrity and reduce storage space, leading to better data consistency.

What does it mean when data in a database is referred to as atomic?

• Each column contains multiple values

• No single column contains more than one value

• The database contains repeating attributes

• The database is not normalised

Answer explanation

When data in a database is referred to as atomic, it means that no single column contains more than one value.

Which of the following statements is true for a database in first normal form?

• It contains repeating attributes

• It is not normalised to any normal form

• It contains no repeating attributes

• It is less efficient than unnormalised databases

Answer explanation

The correct statement for a database in first normal form is that it contains no repeating attributes.

What must a database satisfy in order to meet the second normal form?

• It must remove all key dependencies.

• It must also satisfy first normal form and remove partial key dependencies.

• It must only contain composite primary keys.

• It must eliminate all non-key attributes.

Answer explanation

To meet the second normal form, a database must also satisfy the first normal form and remove partial key dependencies.

What is a partial key dependency?

• It occurs when a non-key attribute depends on only part of a non-composite primary key.

• It occurs when a non-key attribute depends on the whole of the composite key.

• It occurs when a non-key attribute depends on only part of a composite primary key.

• It occurs when a key attribute depends on a non-key attribute.

Answer explanation

A partial key dependency occurs when a non-key attribute depends on only part of a composite primary key, as stated in the correct answer choice.

What is the main requirement for a database to meet the third normal form?

• It must have multi-valued dependencies.

• It must have no non-key dependencies.

• It must conform to first normal form only.

• It must allow null values in primary key fields.

Answer explanation

Meeting the third normal form requires that a database has no non-key dependencies, ensuring each non-key attribute is fully functionally dependent on the primary key.

What type of language is SQL considered to be?

• Procedural

• Declarative

• Object-oriented

• Functional

Answer explanation

SQL is considered to be a declarative language, where users specify what they want to retrieve or manipulate without specifying how to do it.