Chapter 9. Common Design Patterns
The previous chapters described general techniques for building database designs. For example, Chapter 5 explained how to build semantic object models and entity-relationship diagrams for a database, and how to convert those models into relational designs. Chapter 7 explained how to transform those designs to normalize the database.
This chapter takes a different approach. It focuses on data design scenarios and describes methods for building them in a relational model.
In this chapter you learn techniques for:
Providing different kinds of associations between objects.
Storing data hierarchies and networks.
Handling time-related data.
Logging user actions.
This chapter does not provide designs for specific situations such as order tracking or employee payroll. Appendix B, "Sample Database Designs," contains those sorts of examples.
This chapter focuses on a more detailed level to give you the techniques you need to build the pieces that make up a design. You can use these techniques as the beginning of a database design toolbox that you can apply to your problems.
The following sections group these patterns into three broad categories: associations, temporal data, and logging and locking.
Association patterns represent relationships among various data objects. For example, an association can represent the relationship between a rugby team and its opponents during matches.
The following sections describe different kinds of associations.