The Cambridge International Information Technology AS Level syllabus includes a fair amount of theory regarding working with data and specifically working with Relational Databases. An Entity Relationship Diagram (“ERD”) is a logical diagram for visualising a relational database during the design phase.
In this tutorial:
1. Conceptual→Logical→Physical
The diagram below highlights the key differences between Conceptual, Logical and Physical ERD‘s.
1.1 Conceptual
A Conceptual ERD identifies the entities — tables — as well as the attributes — fields — for each of the entities in the model.
1.2 Logical
The Logical ERD adds a column to specify the type of data that will be expected in each field.
1.3 Physical
The Physical ERD includes the tables, fields, data types, field lengths and key fields.
2. Access’ Relationship tool
The Relationship tool in Microsoft Access allows you to create, modify and delete relationships in your database. It provides a view which is essentially a Conceptual ERD.
3. MySQL Workbench
MySQL Workbench is a GUI tool that allows you to create an ERD and then forward engineer the actual MySQL database. Below is a selection of ERD options:
References:
- Brown, G., Sargent, B. (2020). Cambridge International AS Level Information Technology. London: Hodder Education, pp. 260–262