Apress - Pro SQL Server 2008 Relational Database Design and Implementation (2008)03 | CHAPTER 1 INTRODUCTION TO DATABASE CONCEPTS 3 A thorough database design process will undergo four distinct phases as follows Conceptual This is the sketch of the database that you will get from initial requirements gathering and customer information. During this phase you attempt to identify what the user wants. You try to find out as much as possible about the business process for which you are building this data model its scope and most important the business rules that will govern the use of the data. You then capture this information in a conceptual data model consisting of a set of high-level entities and the interactions between them. Logical The logical phase is a refinement of the work done in the conceptual phase transforming what is often a loosely structured conceptual design into a full-fledged relational database design that will be the foundation for the implementation design. During this stage you fully define the required set of entities the relationships between them the attributes of each entity and the domains of these attributes . the sort of data the attribute holds and the range of valid values . Implementation In this phase you adapt the logical model for implementation in the host relational database management system RDBMS in our case SQL Server . Physical In this phase you create the model where the implementation data structures are mapped to physical storage. This phase is also more or less the performance tuning optimiza-tion phase of the project because it is important that your implementation should function in the same way no matter what the physical hardware looks like. It might not function very fast but it will function. It is during this phase of the project that indexes disk layouts and so on come into play and not before this. The first four chapters of this book are concerned with the conceptual and logical design phases and I make only a few references to SQL Server. Generally speaking the logical model of any relational
