Types of Attributes

There are two types of Attributes
Each entity has a single atomic value for the attribute.
For example, SSN or Sex.
The attribute may be composed of several components. For example:

Address(Apt#, House#, Street, City, State, ZipCode, Country), or Name(FirstName, MiddleName, LastName).
Composition may form a hierarchy where some components are themselves composite.
An entity may have multiple values for that attribute. For example, Color of a CAR or Previous Degrees of a STUDENT.

Denoted as {Color} or {Previous Degrees}.

In general, composite and multi-valued attributes may be nested arbitrarily to any number of levels, although this is rare.

For example, Previous Degrees of a STUDENT is a composite multi-valued attribute denoted by

{Previous Degrees (College, Year, Degree, Field)}

Multiple Previous Degrees values can exist. Each has four subcomponent attributes: College, Year, Degree, Field