Thederivedattributeneednotbephysicallystoredinthe

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: s to define as many colors for the car as needed without having to change the table structure. This is the preferred way to deal with multivalued attributes. Creating a new entity in a 1:M relationship with the original entity yields several benefits: it is more flexible, expandable solution, and it is compatible with the relational model. Derived Attributes: A derived attribute or a computed attribute is an attribute whose value is calculated (derived) from other attributes. The derived attribute need not be physically stored in the database. Relationships: A relationship is an association between entities. The entities that participate in a relationship are also called participants. A relationship between entities always operates in both directions. To define the relationship between the entities name, entity relationships may be classified as one‐to‐one, one‐to‐many, or many‐to‐many. Connectivity and Cardinality: Cardinality expresses the minimum and maximum number of tuples associated with one t...
View Full Document

This document was uploaded on 03/07/2014.

Ask a homework question - tutors are online