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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...
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This document was uploaded on 03/07/2014.
- Spring '09