Question Discussion & Solution

🔑 Key Points

• A table is in Second Normal Form (2NF) if it is in 1NF and all its non-prime attributes are fully functionally dependent on every candidate key.
• A partial dependency occurs when a non-prime attribute is dependent on only a part of a candidate key (which is typically a composite key).
• 2NF aims to eliminate these partial dependencies, thus reducing redundancy and update anomalies.
• For example, if {Student ID, Course ID} is a composite key, and 'Student Name' depends only on 'Student ID' (a part of the key), it's a partial dependency.

📄 Additional Information

• To achieve 2NF, you typically decompose the table with partial dependencies into two or more tables.
• One table would contain the full candidate key and its fully dependent attributes, and the other would contain the partial key and the attributes dependent on it.
• Transitive dependency is addressed by Third Normal Form (3NF).

Third Normal Form (3NF) ensures that all non-prime attributes are mutually independent and fully dependent on the primary key.

🔑 Key Points

• Denormalization is the process of intentionally adding redundant data to a previously normalized database.
• It is typically performed to improve query performance by reducing the number of complex joins required to retrieve data.
• This technique is often used in data warehousing or applications where read operations heavily outweigh write operations.
• While it can boost performance, it also reintroduces the risk of data anomalies, so it must be carefully considered and managed.

📄 Additional Information

• The goal of normalization is to reduce redundancy and improve data integrity, while denormalization sacrifices some integrity for performance gains.
• Common denormalization techniques include adding redundant columns, creating summary tables, or merging tables.
• It is a strategic decision made after careful analysis of performance bottlenecks and data usage patterns.