In the modern IT department, an AD tool will most likely be used to develop a database system or an application. Before an AD tool can (or should) be used, all parties involved must under-stand the capabilities and limitations of the tool.
Following are some dependencies of a successful database implementation using an AD tool:
• Management must understand the capabilities of the tool.
• Management must understand the limitations of the AD tool.
• Developers must take advantage of all capabilities of the tool.
• Designers and developers should be trained to use the AD tool.
• Might require initial consulting support for new projects.
• Although an AD tool simplifies many tasks, avoid short cuts throughout the design process.
• Define naming conventions and standards to be used before using the tool.
• Make sure that the tool is compatible with the database software.
• Ensure that developers have sufficient knowledge and experience to use the tool.
Before selecting a tool, try to research the history of the tool and other individuals’ experiences with the tool. Although it is normally best to get the latest version of a tool, you might want to hold off on new versions with dramatic changes until other users have had a chance to find all the bugs.
Summary
Database design is a premeditated effort to gather the requirements of a business and formulate those requirements into a data model. Database design is a meticulous process that requires close attention to detail, involving deep planning, user/customer interaction, and drawing dia-grams that provide a visual representation of business functions and data.
Database design requires much planning. The more time spent identifying the goals of a busi-ness system and planning the actual design process, the less time and frustration will be expended in the long run trying to resolve a poor design. The objectives of the proposed data-base must be clearly defined in order for the development team to properly gather the require-ments. A work plan should be devised to provide guidelines for developers on how the flow of the design project will progress. Milestones should be set, which mark major events throughout the design process. Each milestone should be assigned a projected due date. Before design begins, a design team is formed and tasks are assigned to groups or individuals on the team.
Individuals on the design team submit deliverables to the team leader (the design team can be broken into smaller teams in order to distribute work more efficiently). The customer and man-agement might also require deliverables, such as reports and diagrams used during
user-feedback sessions.
Many aspects of a good database design will only be seen if adequate time is spent planning the design, and the specific steps of the design methodology used are closely followed.
Therefore, a database will be produced that meets the users’ needs. Data stored in a well-designed database will be accurate and easy to maintain. From the administrative perspective, the database will be easy to maintain. Data integrity will be implemented and the constraints that are defined based on the data model will ensure data consistency. Finally, there should be a balance between minimizing redundant data and optimizing database performance.
There are two basic types of modeling: logical and physical. Logical modeling is the process of modeling the activities of a business, and how those activities relate to the business data.
Logical modeling usually involves the generation of business process models and entity rela-tionship diagrams. Physical modeling is the process of converting the logical model, or busi-ness model, into a database model. The entities that exist in the logical model become database tables in the physical modeling. During physical model, also called database design, views and indexes are also defined based on tables that have been defined. The physical model is associ-ated with the physical schema that actually comprises the database objects that the end user will eventually access.
Using automated design tools is the process of using a GUI tool to assist in the design of a database or database application. Many vendors provide a wide variety of AD tools, although the goal of all AD tools is basically the same: to assist the developer during the database and application design to produce a more complete model and reduce the chance for errors during implementation. Many features are common to most AD tools. AD tools typically allow the developer to easily generate diagrams such as process models and entity relationship diagrams.
One of the greatest assets of using an AD tool is that the amount of manual coding to produce DDL or application code is minimized, or does not exist. For example, an AD application may generate all the code you need based on the information supplied to the tool during analysis and design.
Now that the database design has been defined and the goals of the design process have been discussed, it is important to understand the basics of using a particular methodology to design a database. The next chapter discusses design methodologies, the actual process of database design, and the life cycle of a database in detail.