COMM 226 Lecture Notes - Lecture 5: Cardinality, File Descriptor
8 Feb 2015
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Document Summary
Access for multiple users to view the data they need. Database applications: consist of forms, reports, queries and application programs. Entity relationship (e r) data model database & the relationships among those entities. : constituted of entities stored in the: entity: a thing that users want to track can be a physical object or transaction. It has attributes (describe the character of the entity), and an identifier (attribute or group of attributes whose value is associated with one and only one entity). There are different types of relationships (single to single, one to many, single to many, many to many): cardinality: signifies the number of entities that can be involved in relationship. : process of converting a data model into tables, relationships, and data constraints. Normalizing for data integrity can help eliminate data duplication, can be slower to process and is constructed in a way such that every table has single topic.
