Computer Science 1032A/B Lecture Notes - Lecture 2: Unique Key, Cardinality, Foreign Key

• School: Western University
• Department: Computer Science
• Course: Computer Science 1032A/B
• Professor: Louis Magguilli

Document Summary

Task: create a repository (database) for, western, track what courses are offered by which departments, track which faculty is each department in, track what courses the students are enrolled in, track which professor teach which course. If not all of the instances are involved in the relationship: how to read a crow"s foot diagram, 1. Entity: same sequence regardless of reading direction. If one side is mandatory and one is option symbol side, becomes the foreign key: the entity associated with must, is the one that requires the foreign key. Relationship: 1:n if only one side"s many and the other is one, then one must receive the foreign key, n:m. Attributes of relationship connectors always follows the foreign key: relationships can also have attributes, describe properties of the relationship. Dia: attributes: make it a database, create entities, double click, edit the entity properties.