Database Reference
In-Depth Information
CHAPTER 11
COMPLETING THE LOGICAL DESIGN
CHAPTER OBJECTIVES
•
Understand the place and significance of logical design in the database devel-
opment life cycle (DDLC)
•
Study how data modeling fits in with logical design
•
Review the various steps necessary to complete logical design
•
Focus on logical design for the relational data model
•
Learn how to document the logical design effort
In Chapter 4, while covering the database development life cycle (DDLC), we
briefly discussed the design phase. The ultimate goal of a database development
project is to have proper data content and structures in the database system. You
must make sure that all the necessary real-world information requirements for your
organization are correctly included in the database system. Before you determine
how to do this and create a design, you need to know exact details about the real-
world information—its exact nature and extent and how the information is used to
run the business. You find out the details during the requirements definition phase.
Once you have the details of all the information requirements, somehow you have
to represent all of this in your design of the database system.
How do you keep data in the database? Data are stored in physical storage in
the form of records, blocks, and files. Therefore, to properly store data in the data-
base, you need to design the files, blocks, and records. This part of the design phase
relates to the physical design of the database. Physical design must consider the
stipulations of the DBMS selected for your organization. The selected DBMS lays
down conditions, rules, and formats for the file structures.
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