ITM 500 Lecture 6: Module 06 Introduction to Data Modeling

• School: Ryerson University
• Department: Information Technology Management
• Course: ITM 500
• Professor: Raymond Moss

Document Summary

The entity relationship diagram (erd) is a graphical representation of the relational. The model represents the logical view of the data from the user perspective. The approach to designing this logical model is centred on the principle of minimising data redundancy and therefore maximising data consistency. The basic building block of the database at the logical level is known as an entity. An entity can be considered as a meaningful grouping of like data. Whether a grouping is meaningful is not an absolute idea but is determined by the interests of the end-user and how they perceive and utilise their data. What may be meaningful to one user may not be true for another. Entities are generally groupings associated with people, places, things and events. Some entities will be very concrete such as student or product; others may be more abstract such as job history or medical appointment. The data characteristics associated with an entity are known as attributes.