Summary of Lecture 2:

ER Models and Normalisation models can be used to represent information. An ER Model (Entity Relationship Model) is the model that was covered within thodays lecture, and a normalisation model will be covered later. Within Entity Relationship models, there are a few elements that make up the diagram:
Entity - An object/thing.; E.g. Book, Student, Shop
Attributes - A "something" within an entity table. E.g. An ID Number for a student.
Occurence of Entity - One line within the entity.
Primary Key - A unique identifier/field within an entity. E.g. Student ID within a Student Entity.
Enterprice Rules - A list of regulations that the client mst abide by.
Relationship - A list between 2 or more entities.

4 Principles of ER Modelling:
Identification of entities (Structure/Relationships).
Construction of a process independant model of the stored data requirements.
Construction of a robust data model.
The construction of a logical model of the data.

6 Steps of ER Modeling:
Identify the entities.
Identify the attributes within the entities.
Put data in logical groups.
Identify the primary key(s) within each entity.
Elimate some of the attributes.
Use relationships to create the relationship model.

Crows Feet:
One to One - -----------------
Many to One - >---------------- or -------------------<
Many to Many - >------------------<