tailieunhanh - Hướng dẫn học Microsoft SQL Server 2008 part 56

Tạo lược đồ cơ sở dữ liệu của vật lý ông còn làm việc với cơ sở dữ liệu, tôi càng trở nên thuyết phục rằng các ảo thuật thực sự là các lược đồ vật lý thiết kế. Không có khía cạnh của phát triển ứng dụng có nhiều tiềm năng để làm chệch một ứng dụng hoặc cho phép nó bay cao hơn so với các lược đồ vật lý - không lập chỉ mục. | . . - A- f . - v r A v Ab Xiv V SC w SS Vi .U. i . KE - W -Ui- A Creating the Physical cj y Database Schema MK i .M .Wv- v . .w- The longer I work with databases the more I become convinced that the real magic is the physical schema design. No aspect of application development has more potential to derail an application or enable it to soar than the physical schema not even indexing. This idea is crucial to my view of Smart Database Design as expressed in Chapter 2 Data Architecture . The primary features of the application are designed at the data schema level. If the data schema supports a feature then the code will readily bring the feature to life but if the feature is not designed in the tables then the client application can jump through as many hoops as you can code and it will never work right. The logical database schema discussed in Chapter 3 Relational Database Design is a necessary design step to ensure that the business requirements are well understood. However a logical design has never stored nor served up any data. In contrast the physical database schema is an actual data store that must meet the Information Architecture Principle s call to make information readily available in a usable format for daily operations and analysis by individuals groups and processes. It s the physical design that meets the database objectives of usability scalability integrity and extensibility. This chapter first discusses designing the physical database schema and then focuses on the actual implementation of the physical design Creating the database files Creating the tables Creating the primary and foreign keys Creating the data columns Adding data-integrity constraints IN THIS CHAPTER Creating the database files Creating tables Creating primary and foreign keys Configuring constraints Creating the user data columns Documenting the database schema Creating indexes 513 Part IV Developing with SQL .