System requirements analysis
The first step in developing a database model using ER modeling is to consider the requirements of the system. The requirements for the online winestore were described in Chapter 1 and are typically gathered from a scope document, customer interviews, user requirements documents, and so on.
Many of the requirements affect development of the ER model, while others are more general system requirements used to develop the web database application. One of the skills of ER modeling is extracting the requirements that impact on the database design from those that are functional elements of the system.
Once a system requirements analysis is complete, and the detailed requirements written down, you can proceed to the conceptual database design using the ER modeling techniques.