✏️ Explanatory Question
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.