Identify the requirements of First, Second, and Third Normal Forms
This exercise asked you to match first, second, and third normal forms to their respective requirements.
The proper matches are listed below:
First normal form: The relation cannot contain any repeating groups.
Second normal form: Every field in the relation must be functionally dependent upon the entire primary key.
Third normal form: The relation cannot contain any transitive dependencies.
2nd Normal Form Definition
A database is in second normal form if it satisfies the following conditions:
- It is in first normal form
- All non-key attributes are fully functional dependent on the primary key
In a table, if attribute B is functionally dependent on A, but is not functionally dependent on a proper subset of A, then B is considered fully functional dependent on A.
Hence, in a 2NF table, all non-key attributes cannot be dependent on a subset of the primary key.
Note that if the primary key is not a composite key, all non-key attributes are always fully functional dependent on the primary key.
A table that is in 1st normal form and contains only a single key as the primary key is automatically in 2nd normal form.
3rd Normal Form Definition
A database is in third normal form if it satisfies the following conditions:
- It is in second normal form
- There is no transitive functional dependency
By transitive functional dependency, we mean we have the following relationships in the table:
A is functionally dependent on B, and B is functionally dependent on C. In this case, C is transitively dependent on A via B.
If you have any questions about the requirements for first, second, or third normal forms in general or about this page,
enter your query into the Search box above on this site.