ISYS114 Lecture Notes - Lecture 2: Business Rule, Associative Entity, Foreign Key

• School: Macquarie University
• Department: Information Systems
• Course: ISYS114
• Professor: Charanya

Document Summary

Explanation of a term or fact term: word or phrase with specific meaning and fact: association between two or more terms. Guidelines for good data definition: a concise description of essential data meaning, gathered in conjunction with systems requirements, accompanied by diagrams, and achieved by consensus, and iteratively refined. Entities: entity instance person, place, object, event, concept (often corresponds to a row in a table), entity type (often corresponds to a table). Relationships: relationship instance link between entities (corresponds to primary key foreign key equivalencies in related tables), relationship type category of relationship link between entity types. Attributes: properties or characteristics of an entity or relationship type (often corresponds to a field in a table). Are statements that define or constrain some aspect of the business. Are expressed in terms familiar to end users. Entity a person, a place, an object, an event, or a concept in the user environment about which the organisation wishes to maintain data.