This excerpt from Teach Yourself Database Design focuses on some basic concepts associated with the database design process. Before a design effort can proceed full speed ahead, the designer must first take time to understand the business. Understanding the business involves understanding the entities, data, and rules within an organization, and then converting these attributes of the business into a business model. Then, the designer must have a solid comprehension of the proposed database model. Finally, the designer will convert the business model into a database model, using a design methodology, whether automated or a manual process.
The following subsections briefly describe these topics: design methodology, converting the business model to design, and application design.
A design methodology is the approach taken toward the design of a database. It is the process of designing a database with a sound plan from the beginning. For individuals lacking the proper knowledge and experience, designing a database probably involves a great deal of trial and error. If an individual understands database fundamentals and design concepts, the basic steps of the database design process, and has a structured plan (has selected a design methodology), the design process should produce a quality product to the customer.
Some of the advantages of using a design methodology include:
- It provides a step by step guide toward database design.
- Little or no trial and error is involved.
- It is easy to document the database and application with the availability of design plans, drawings depicting the organization's needs, and other deliverables specified.
- It is easy to modify the database in the future as organization and planning eases the tasks of managing changes.
Converting the Business Model to Design
Database design is the process of converting business objects into tables and views. It is the process of actually designing a database based on a business model. Business model components such as entities and attributes are converted into tables and columns. Constraints are added to columns where necessary in order to enforce data and referential integrity. Views of tables might be created in order to filter the data that a user sees, or to simplify the query process. After the design of a database is complete, the entire business model (business processes, rules, and entities) will have been converted into a functional database in which corporate data can be stored, modified, and easily retrieved.
Application design is the process of creating an interface for the end user through which the database can be accessed. It is the process of transforming business processes that have been defined into a usable application through which the end user can easily access information in the database. A typical application might consist of a set of forms that allow the end user to create new records in the database, update or delete existing records, or perform queries. The application might also include canned queries and reports. Common tools used to develop an application include Oracle Designer, Oracle Developer/2000, Visual Basic, C++, and PowerBuilder. Application design, although an essential part of the overall design process, is out of the scope of this book. This book focuses on the database design process versus application design--although the design of an application is an integral supplement to the database itself.
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