| Normal form
| Rule
| Example of rule violation
|
| First
| A relation cannot have repeating fields or groups.
| <author(1), author(2)..., title>
|
| Second
| +
every nonkey field must be functionally dependent
on all of the key.
| <part, warehouse, quantity, warehouse-address>
where the key is "part", "warehouse"
|
| Third
| +
a nonkey field cannot be functionally dependent
on another nonkey field.
| <employee, department, department-location>
where the key is "employee"
|
| Fourth
| A relation cannot contain two or more
independent multivalued attributes of an entity
| <employee, skill, language>
where the key is "employee", "skill",
"language"
|
| Fifth
| Roughly, a relation cannot be reconstructed
from several relations each having fewer fields
and not all having the same key
| <salesperson, product, client>
where it is known that, if a salesperson sells a product
and sells to a client,
then that salesperson sells that product to that client
|
In any relation,
attribute A is 
Home