The fourth phase of the database-design process involves establishing table relationships. You conduct interviews with users and management once again, identify relationships, identify relationship characteristics, and establish relationship-level integrity.
Working with users and management is a prudent exercise because they can assist you in identifying relationships among the data. You cannot possibly be familiar with every aspect of the data your organization uses, so leveraging whatever knowledge they have about the data they use will be very beneficial to you.
After you've identified the relationships, you establish a logical connection between the tables in each relationship with a primary key or with a linking table. What you actually use depends upon the type of relationship you're establishing between the tables. Next, you determine the type of participation and degree of participation for the tables in each relationship. In some cases, these participation characteristics will be obvious to you due to the nature of the data stored in the tables. In other cases, you'll base the participation characteristics on specific business rules.