WHAT

Before programming begins the Entity Relationship Diagram (ERD) should be defined.

WHY

The ERD should be designed so that we have a blueprint to work with when we actually create the database.

In this stage we can define tables, columns, indexes, primary keys, relations etc etc.

The ERD will help us to normalise the database by refactoring. Normalisation is one step in optimising the database.

HOW

• Examine the requirements, user stories and tasks to get the required fields and relationships between entities.
• With pen and paper or a whiteboard define each entity separately with all the fields you can think of.
• Map the relationships between each entity.
• Normalise to first normal form (1NF).