DBMS Normalization Quiz

Study Notes

DBMS NORMALIZATION

First Normal Form (1NF)

Definition: A relation is in 1NF if all underlying attributes contain atomic values; no repeating groups or arrays.
Requirements:
- Each table cell must contain a single value (atomic value).
- Each record must be unique, with a primary key.
- Each column must contain values of a single type.
Example:
- Not in 1NF:
  - Student (ID, Name, Courses)
  - (1, John, {Math, Science})
- In 1NF:
  - Student (ID, Name, Course)
  - (1, John, Math)
  - (1, John, Science)

Third Normal Form (3NF)

Definition: A relation is in 3NF if it is in 2NF and all the attributes are functionally dependent only on the primary key.
Requirements:
- Remove any transitive dependency (non-prime attributes depending on other non-prime attributes).
- Must be in Second Normal Form (2NF).
Example:
- Not in 3NF:
  - Student (ID, Name, Dept_ID, Dept_Name)
- In 3NF:
  - Student (ID, Name, Dept_ID)
  - Department (Dept_ID, Dept_Name)

Boyce-Codd Normal Form (BCNF)

Definition: A relation is in BCNF if it is in 3NF and for every functional dependency X → Y, X is a super key.
Requirements:
- Addresses anomalies that 3NF does not cover (where non-key attributes can depend on parts of a composite key).
Example:
- Not in BCNF:
  - Course (Course_ID, Instructor, Room)
  - If Instructor → Room but Instructor is not a super key.
- In BCNF:
  - Separate Instructor information into another table.

Denormalization Techniques

Definition: The process of intentionally introducing redundancy into a database to improve performance.
When to Denormalize:
- When read performance is more critical than write performance.
- When frequent complex queries lead to high join costs.
Techniques:
- Combining Tables: Merge tables that are frequently accessed together.
- Redundant Storage: Store derived or computed attributes to speed up access.
- Adding Redundant Foreign Keys: Add foreign keys to avoid joins when necessary.
Considerations:
- Supports optimization for specific query patterns.
- Increases the complexity of data integrity management due to redundancy.

First Normal Form (1NF)

Each table cell should contain only one value, known as an atomic value.
Tables must have a unique primary key for each record.
All cells within a single column should have the same datatype.
Avoid repeating groups or arrays within a table.

Third Normal Form (3NF)

A relation is in 3NF if it meets the requirements of 2NF and all its attributes are directly dependent on the primary key.
Eliminating transitive dependencies is crucial, ensuring no non-prime attributes depend on other non-prime attributes.

Boyce-Codd Normal Form (BCNF)

A relation in BCNF meets the requirements of 3NF and ensures that for every functional dependency X → Y, X is a super key.
This form addresses anomalies not covered by 3NF, where non-key attributes might depend on parts of a composite key.

Denormalization Techniques

Intentional introduction of redundancy into a database to improve performance.
Denormalization is advantageous when read performance is more critical than write performance or complex queries lead to high join costs.
Techniques include combining tables frequently accessed together, storing derived attributes for faster access, and adding redundant foreign keys to avoid joins.
While denormalization optimizes for specific query patterns, it increases the complexity of data integrity management due to redundancy.

Description

Test your knowledge on Database Management System normalization concepts, focusing on First Normal Form (1NF) and Third Normal Form (3NF). This quiz will cover definitions, requirements, and examples to help you understand how to structure relational databases effectively.