Lesson 10 | Achieving 2NF |
Objective | Describe the process for achieving 2NF. |
Achieving Second Normal Form
General requirements for Second Normal Form:
- Remove subsets of data that apply to multiple rows of a table and place them in separate tables.
- Create relationships between these new tables and their predecessors through the use of foreign
The next lesson describes the limitations of second normal form.
Functional dependencies versus Entities
When it comes to deciding what is driving database design, 1) functional dependencies or 2) entities, this question is really a chicken and egg problem.
What is most important is that there is consistency between the ER diagram and the functional dependencies you identify in your relations. It makes no difference whether you design by looking for functional dependencies or for entities.
In most cases database design is an iterative process (as mentioned in the database life cycle) in which you create an initial design, check it, modify it, and check it again.
You can look at either functional dependencies and/or entities at any stage in the process, checking one against the other for consistency
Second Normal Form - Exercise