Database Normalization

In a database project for their school, Kai and Maya are discussing the purpose of database normalization. What do they conclude?

• To simplify database queries by merging tables.

• To increase data redundancy for faster access.

• The purpose of database normalization is to minimize data redundancy and ensure data integrity.

• To enhance the visual representation of data in reports.

Answer explanation

The correct choice highlights that database normalization aims to minimize data redundancy and ensure data integrity, which are essential for maintaining a clean and efficient database structure.

William is organizing a database for his school project. He wants to ensure that the database is structured properly. Define the First Normal Form (1NF).

• A table is in First Normal Form (1NF) if it has a primary key and contains only atomic values, with no repeating groups.

• A table is in First Normal Form (1NF) if it allows repeating groups of data.

• A table is in First Normal Form (1NF) if it contains non-atomic values.

• A table is in First Normal Form (1NF) if it has multiple primary keys.

Answer explanation

A table is in First Normal Form (1NF) if it has a primary key and contains only atomic values, with no repeating groups. This ensures data integrity and simplifies data retrieval.

Lily is trying to organize her class notes into a table format. What are the requirements for a table to be in 1NF?

• A table is in 1NF if it has duplicate column names.

• A table is in 1NF if it has atomic values, unique column names, and consistent data types in each column.

• A table is in 1NF if it allows multi-valued attributes.

• A table is in 1NF if it has no primary key.

Answer explanation

A table is in 1NF if it has atomic values (no multi-valued attributes), unique column names, and consistent data types in each column. This ensures data integrity and eliminates redundancy.

Isla is studying database design and wants to understand the Second Normal Form (2NF).

• A table is in Second Normal Form (2NF) if it is in First Normal Form (1NF) and all non-key attributes are fully functionally dependent on the primary key.

• A table is in Second Normal Form (2NF) if all attributes are dependent on any candidate key.

• A table is in Second Normal Form (2NF) if it contains duplicate rows.

• A table is in Second Normal Form (2NF) if it has no primary key.

Answer explanation

A table is in Second Normal Form (2NF) if it meets the criteria of First Normal Form (1NF) and ensures that all non-key attributes are fully functionally dependent on the primary key, preventing partial dependencies.

Ava is studying database normalization and wants to understand the main difference between 1NF and 2NF. Can you help her?

• 1NF allows duplicate rows, while 2NF does not.

• 1NF focuses on atomicity of data, while 2NF addresses partial dependencies on the primary key.

• 1NF requires a primary key, while 2NF does not.

• 1NF is concerned with data types, while 2NF focuses on normalization levels.

Answer explanation

The correct choice highlights that 1NF ensures data is atomic, meaning each value is indivisible, while 2NF eliminates partial dependencies, ensuring that all non-key attributes are fully functionally dependent on the primary key.

Give an example of a table that is in 1NF but not in 2NF, considering students enrolled in different courses.

• | StudentID | CourseID | StudentName | Instructor | | 1 | 101 | Abigail | Prof. X | | 2 | 101 | Abigail | Prof. Y | | 2 | 102 | James | Prof. Y |

• | StudentID | CourseID | StudentName | | 1 | 101 | Abigail | | 1 | 102 | Abigail | | 2 | 101 | Arjun |

• | StudentID | CourseID | Instructor | | 1 | 101 | Prof. X | | 1 | 102 | Prof. Y | | 2 | 101 | Prof. X |

• | StudentID | CourseID | StudentName | Instructor | |-----------|----------|--------------|------------| | 1 | 101 | Abigail | Prof. X | | 1 | 102 | Abigail | Prof. Y | | 2 | 101 | James | Prof. X |

Answer explanation

The correct choice shows a table in 1NF with repeating groups (StudentID and CourseID) but not in 2NF, as StudentName and Instructor depend only on StudentID, not on the full primary key (StudentID, CourseID).

In a classroom, Charlotte and Liam are discussing the concept of functional dependency in the context of normalization. What does Charlotte explain to Liam?

• A functional dependency states that if two tuples have different values for attribute A, they must have different values for attribute B.

• A functional dependency indicates that if two tuples have the same value for attribute A, they must have the same value for attribute B.

• A functional dependency means that all attributes in a relation are independent of each other.

• A functional dependency indicates that the value of attribute A can determine the value of any other attribute in the relation.

Answer explanation

A functional dependency indicates that if two tuples have the same value for attribute A, they must have the same value for attribute B. This is crucial for normalization as it helps identify relationships between attributes.

How does normalization help in reducing data redundancy in a school database where student records are maintained?

• Normalization reduces data redundancy by structuring data to ensure each piece is stored only once, eliminating duplicates.

• Normalization combines all data into a single table to reduce redundancy.

• Normalization increases data redundancy by duplicating information across tables.

• Normalization has no effect on data redundancy in databases.

Answer explanation

Normalization helps reduce data redundancy by organizing data into tables in a way that each piece of information is stored only once, thus eliminating duplicates. This ensures efficient data management and integrity.

In a database project for a school, what are the potential drawbacks of over-normalization?

• Simplified data structure

• Improved data retrieval speed

• Enhanced data security

• Potential drawbacks of over-normalization include increased complexity, performance issues, and difficulties in data management.

Answer explanation

The correct choice highlights that over-normalization can lead to increased complexity, performance issues, and difficulties in data management, which are significant drawbacks compared to the benefits of simplified structures or improved speed.

In a database project for their class, Henry, Arjun, and Luna are discussing the different normal forms in database normalization.

• 1NF, 2NF, 3NF, BCNF, 4NF, 5NF

• 1NF, 2NF, 3NF, 4NF, 5NF, 8NF

• 1NF, 2NF, 3NF, 4NF, 5NF, 7NF

• 1NF, 2NF, 3NF, 6NF

Answer explanation

The correct answer is '1NF, 2NF, 3NF, BCNF, 4NF, 5NF' as these are the recognized normal forms in database normalization. BCNF (Boyce-Codd Normal Form) is an important form that addresses certain anomalies not covered by 3NF.