Database Design - Customers

Most business applications have a customer table. As a developer it is all too easy to create a customer table and tie it to sales or orders. This approach can be short sighted. Before jumping in to table design ask yourself and the business some questions:

• What is the life cycle of a customer?
• When does a customer become a customer? When they place an order? What if you have the contact information before that? Is the customer still a customer or is it a lead?
• If a customer hasn't purchased anything for 5 years are they still a customer?

Something else to consider- customer contact information becomes outdated very quickly. The Sales & Marketing institute found that by surveying attendees at seminars, 70.8% of the attendees business cards had at least one piece of information that was out of date.

While not all customer information can be validated, addresses can. Customer addresses should be routinely validated and the date and result of the validation should be stored.

Before you design that next customer table, think about the business process and what data might be in the table several years down the road.