Maria Lourdes C. Capilitan
SysAnal(O0A)
August 5, 2008
Book Review
Systems Analysis and Design Methods
(4th Edition)
Jeffrey L. Whitten, Lonnie D. Bentley
QA 76.9 S88 W 48
Quote(Chapter 11): “As General Rule, Combining entities into tables is not recommended.”
The Database Schema
The data base schema:
- It is the physical model for a database.
- It also represents the technical implementation of the logical data model.
- The design of a data base depicted as a special model.
Relational Database Schema
Relational Database Schema:
- The database structure in terms of tables, keys, indexes and integrity rules.
- Specifies details based on the capabilities, terminologies and constraints of the chosen database management system.
Rules and guidelines in transformation of logical data types into physical relational database schema:
- Each fundamental, associative and weak entity is implemented as a separate table. Table names may have to be formatted according to the naming rules and size limitations of the DBMS.
· Primary key is identified and implemented as an index into the table.
· Secondary key is implemented as its own index into the table.
· Foreign key will be implemented as such.
· Attributes will be implemented with fields.
Names in Physical Database:
· Data Type
· Size of Field
· Null or Not Null
· Domains
· Default
- Super Type/ Sub Type entities present additional options as:
- Case tools do not currently support object like constructs such as super types and sub types.
- If sub types are similar size and data content. A database administrator may elect to collapse. The sub types into the super type to create a single table.
- Evaluate and Specify referential integrity constraints
Sound Stage Database Schema was automatically generated from logical data model by case tool system architect.
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