A Level Computer Science OCR Practice Exam

What issue does a many-to-many relationship pose during database design?

1. It decreases the performance of queries

2. It cannot exist in a normalized form

3. It complicates the implementation of foreign keys

4. It always results in an inappropriate table structure

The correct answer is: It cannot exist in a normalized form

A many-to-many relationship in database design presents a challenge because such relationships cannot be directly implemented with a single table. In a relational database, normalization is a key process that aims to eliminate redundancy and ensure data integrity. When you have a many-to-many relationship, it indicates that multiple records in one table can relate to multiple records in another table. To effectively manage this type of relationship while adhering to normalization principles, it is necessary to introduce a junction table (also known as a bridge table). This junction table serves to establish the association between the two original tables and often includes foreign keys referencing the primary keys of both tables. By creating this additional layer, the data structure becomes more organized and adheres to rules of normalization. The inability to maintain a many-to-many relationship without this additional structure highlights the fundamental requirement for normalization in relational database design, confirming why the answer indicates that it cannot exist in a normalized form.