Second Normal Form (2NF)
Recall the summary of all three normalization levels: Every data element must provide a fact about the key, the whole key, and nothing but the key. First Normal Form (1NF) is the “Every data element must provide a fact about the key” part. Second Normal Form (2NF) is “the whole key” part. This means each entity must have the minimal set of data elements that uniquely identifies each entity instance.
For example, in Figure 18.12, we have Employee Assignment.
Figure 18.12 Example of Model not in 2NF
The primary key of Employee Assignment is Employee Identifier and Department Identifier. Do we have the minimal primary key ...