What is Identifying and descriptive attributes?

The attributes that are indivisible are known as

In some cases, two or more attribute values are related in such a way that the value of one attribute can be determined from the value of other attributes or related entities. Consider an entity type PERSON and its attributes Date_of_birth and Age. The value of the attribute Age can be determined from the current date and the value of Date_of_birth. Thus, the attribute Age is known as a derived attribute and the attribute Date_of_birth is known as a stored attribute.

The attributes that can have only one value for a given entity are called the

The attributes that are formed by arbitrarily nesting the composite and multivalued attributes are called complex attributes. This is represented by grouping the components of a composite attribute between parentheses ‘()’ and by displaying the multi-valued attributes between braces ‘{}’, and attributes separated by commas. For example, a publisher can have offices at different places, each with different addresses and each office having multiple phones (Figure below).