Database Systems: Design, Implementation, and Management Chapter 9 Database Design

The Systems Development Life Cycle (SDLC) Traces history (life cycle) of information system Database design and application development mapped out and evaluated Iterative rather than sequential process 2

JMSB BTM and the SDLC 3 BTM Minor Entire SDLC

Technology Acceptance Model Davis, F. D. (1989). Perceived usefulness, perceived ease of use, and user acceptance of information technology. MIS Quarterly, 13(3),

Two fundamental issues in deciding how much functionality to implement in a new system How much functionality should you implement? (Perceived Usefulness) 1.Baseline replication: The new system must at least be as functional as the old one 2.User-requested functionality: The system should add new features required by users 3.Analyst-suggested functionality: The system may optionally go beyond users’ expectations How much retraining effort would it take users to learn to use the new system? (Perceived Ease of Use) 1.Baseline replication: Minimal effort, or net zero effort (takes no more effort than time and effort saved from switching from old system) 2.User-requested functionality: Users must feel that new retraining is worthwhile considering the benefits they have asked for 3.Analyst-suggested functionality: No extra retraining should be required, unless users are absolutely convinced of benefits of extended functionality 5

The Database Life Cycle (DBLC) Six phases: –Database initial study –Database design –Implementation and loading –Testing and evaluation –Operation –Maintenance and evolution 6

Conceptual Design Creating a detailed, validated ERD Independent of RDBMS chosen

DBMS Software Selection Critical to information system’s smooth operation Common factors affecting purchasing decisions: –Cost –DBMS features and tools –Underlying model –Portability –DBMS hardware requirements lational_database_management_systemshttp://en.wikipedia.org/wiki/Comparison_of_re lational_database_management_systems 8

Logical Design Specifying the tables, attributes and keys Specifying the domain integrity and attribute constraints Dependent on chosen RDBMS

Physical Design Dependent on chosen hardware

Top-down versus bottom-up database design strategies Top-down design –Identifies groups of entities –Defines data elements for each of those groups Definition of different entity types Definition of each entity’s attributes Bottom-up design –Identifies data attributes (items) –Groups them together into entities, and then larger groups 11

Centralized vs. decentralized design Centralized design –When data component is composed of small number of objects and procedures –Typical of small systems Decentralized design –Data component has large number of entities –Complex relations on which complex operations are performed –Problem is spread across several operational sites 12

Sources Most of the slides are adapted from Database Systems: Design, Implementation and Management by Carlos Coronel and Steven Morris. 11th edition (2015) published by Cengage Learning. ISBN 13: Database Systems: Design, Implementation and Management Other sources are noted on the slides themselves 13