Computer Science 1032A/B Lecture Notes - Unique Key, Calendar Date, Social Insurance Number

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

Document Summary

Entities: rectangles: each entity has a unique id number (primary key, name, location etc. Attributes: ovals: key attributes, uniquely identifies an entity or relationship, identified by being underlined. Relationships: diamonds: each relationship has 3 properties, attributes. Key attribute - if unique, underline (social insurance number) Write that number on top, write m for many, n= many to many. Cannot have m to m have to have m to n: participation. Example: faculty would be in a rectangle, is a chair of would be in a diamond, and department would be in a rectangle. Designing an e-r diagram: collect and review all the data. 3: decide on the relationships and draw lines between the entities, including any. Identify entities and attributes and draw them on your er diagram. Identify the key attributes and underline them on your diagram attributes of the relationships: decide on the cardinality of each relationship and add it to the diagram.