tailieunhanh - Beginning Database Design- P20

Beginning Database Design- P20:This book focuses on the relational database model from a beginning perspective. The title is, therefore, Beginning Database Design. A database is a repository for data. In other words, you can store lots of information in a database. A relational database is a special type of database using structures called tables. Tables are linked together using what are called relationships. You can build tables with relationships between those tables, not only to organize your data, but also to allow later retrieval of information from the database | 12 Business Rules and Field Settings In business or in life don t follow the wagon tracks too closely. H. Jackson Brown Database modeling analysis and design are an art form. Use your imagination and you might find that sometimes rules are made to be bent if not broken altogether This chapter covers the deepest layer of implementation into a database model business rules. Business rules are implemented into a database model by creating tables establishing relationships between tables identifying fields their datatypes and various other factors including things such as validation. Field settings including display formats input maskings default values and check constraints are included. There is also a brief section on applying business rules by way of storing code in the database model. This chapter is the last of four chapters using the case study example of the online auction house. By reading through the last few chapters and this one you should have a good idea of the analysis and design process for both OLTP and data warehouse database models all the way through from start to finish. By the end of this chapter you should know how to apply field setting business rules in the extreme and also that this extreme might be best left to application Software Development Kits SDKs . Application SDKs are much more powerful than database modeling methods when it comes to number crunching and some of the more detailed aspects of database modeling. In this chapter you learn about the following Database model business rules classification Implementation of business rules can be implemented as table and relations links between tables design Using individual field settings as applications of deeper level business rules Using stored database code to implement highly complex business rules Chapter 12 What Are Business Rules Again When applied as a database model the business rules of a company become the structure of that database model. The most basic implementation of business