Relational Databases - Java Database Programming Bible - page 15

Table 1-9: Inventory Table in 2NF

Name Warehouse Description Qty Cost

Corn Flakes Warehouse #2 Cereal 178 1.95

Rice Krispies Warehouse #2 Cereal 97 1.95

Rice Krispies Warehouse #7 Cereal 103 2.05

Oatmeal Warehouse #7 Cereal 15 0.98

Table 1-10: Warehouse Table in 2NF

Warehouse Address

Warehouse #2 123 Pine

Warehouse #7 24 Holly

In summary, the second normal form requires that any data that is not directly related
to the entire key should be removed and placed in a separate table or tables. These
new tables should be linked to the original table using foreign keys. In the example of
Tables 1 -9 and 1-10 , the Warehouse column is both part of the primary key of Table
1-9 , and the foreign key pointing to Table 1 -10 .

Third normal form

The requirements of the third normal form are as follows:

The table must be in second normal form.

The table cannot contain fields that are not related to the primary key.

Third normal form is very similar to second normal form, with the exception that it
covers situations involving simple keys rather than compound keys. In the example
used to explain the second normal form, a compound key was used because
inventory items of the same type, such as Rice Krispies, could have different
attributes such as Warehouse number. If you are tracking unique items, such as
employees, you can have a similar situation, but with a simple key, as shown in Table
1-11 :

Table 1-11: Employee Table

Name Department Location

Jones Sales 43 Elm

Smith Production 17 Main

Williams Shipping 123 Pine