DBMS DESIGN PROCESS

Tayyab Hameed, Univseristy of Lahore, Islamabad CampusMIS

Database & Management System Database

Carefully designed and constructed repository of facts.

Part of an information system. Management System

A management system is the framework of processes and procedures used to ensure that an organization can fulfill all tasks required to achieve its objectives.

Database Management System A database management system (DBMS) is a collection of

programs that enables an organization to store, modify, and extract information from a database.

Types of DBMS There are different types of DBMSs:

Small systems that run on personal computers. Huge systems that run on main frames.

The following are examples of database management systems: Computerized library Flight reservation systems Inventory management systems and many more……

Database Design The process of producing a detailed data model of a database

containing all the needed logical and physical design choices and physical storage parameters needed to generate a design of a database.

Database design must reflect the IS, of which the database is a part. Information systems undergo evaluation and revision within a

framework known as the Systems Development Life Cycle (SDLC). Databases also undergo evaluation and revision within a framework

known as the Database Life Cycle (DBLC). There are two general design strategies exist:

Top-down vs. bottom-up design Centralized vs. decentralized design (Con’t.)

DBMS Design Process

User

(Someone doing “real work” )

Infrastructure(Computer and Human)

Management(Organization)

Successful DBMS design requires an interlocking of the :

Systems Development Life Cycle

(Con’t.)

Systems Development Life Cycle Planning

Should the existing system be continued, modified or replaced?

The technical of hardware and software requirements. The system cost.

Analysis What are the precise requirements of the current

system’s end users? Do these requirements fit into the overall information

requirements? (Con’t.)

Systems Development Life Cycle Detailed System Design – the designer completes

the design of the system’s processes including all the necessary technical specifications for the screens, menus, reports, and other devices that might be used in help to make the system a more efficient information generator.

Implementation Install the hardware, the DBMS software, and application

programs. The system enters into a cycle of coding, testing, and

debugging, until it is read to delivered. (Con’t.)

Systems Development Life Cycle

The actual database is created, and the system is customized, by using a variety of methods and devices: Customized user programs Database interface programs Conversion programs that import the data from a different file

structure, using batch programs, a database utility, or both. Maintenance

Corrective maintenance in response to system errors. Adaptive maintenance due to changes in the business

environment. Perfect maintenance to enhance the system.

Database Design

(Con’t.)

Database Lifecycle (DBLC)

(Con’t.)

Phase 1: Database Initial Study Purposes

Analyze company situation Operating environment Organizational structure

Define problems and constraints Define objectives What is the proposed system’s initial

objective? Will the system interface with other existing or future systems

in the company? Will the system share the data with other systems or users?

Define scope and boundaries (Con’t.)

Initial Study Activities

(Con’t.)

Phase 2: Database Design Most Critical DBLC phase Makes sure final product meets requirements Focus on data requirements Sub-phases

I. Create conceptual design II. DBMS software selection III. Create logical design IV. Create physical design (Con’t.)

I. Conceptual Design Data modeling creates abstract data

structure to represent real-world items High level of abstraction Four steps

Data analysis and requirements Entity relationship modeling and normalization Data model verification Distributed database design

(Con’t.)

Data analysis and Requirements

Data analysis and Requirements Focus on:

Information needs Information users Information sources Information constitution

Data sources Developing and gathering end-user data views Direct observation of current system Interfacing with systems design group Business rules (Con’t.)

II. DBMS Software Selection DBMS software selection is critical Advantages and disadvantages need study Factors affecting purchasing decision

Cost DBMS features and tools Underlying model Portability DBMS hardware requirements (Con’t.)

III. Logical Design Translates conceptual design into internal model Maps objects in model to specific DBMS constructs Design components

Tables Indexes Views Transactions Access authorities Others

(Con’t.)

IV. Physical Design Selection of data storage and access

characteristics Very technical More important in older hierarchical and network

models Becomes more complex for distributed

systems Designers favor software that hides physical

details (Con’t.)

Phase 3: Implementation and Loading

Creation of special storage-related constructs to house end-user tables. Data loaded into tables. Other issues:

Performance Security Backup and recovery Integrity Company standards Concurrency controls (Con’t.)

Phase 4: Testing and Evaluation Database is tested and fine-tuned for

performance, integrity, concurrent access, and security constraints

Done in parallel with application programming Actions taken if tests fail

Fine-tuning based on reference manuals Modification of physical design Modification of logical design Upgrade or change DBMS software or hardware (Con’t.)

Phase 5: Operation Database considered operational Starts process of system evaluation Unforeseen problems may surface Demand for change is constant

(Con’t.)

Phase 6: Maintenance and Evaluation

Preventative maintenance Corrective maintenance Adaptive maintenance Assignment of access permissions Generation of database access statistics to monitor

performance Periodic security audits based on system-generated

statistics Periodic system usage-summaries (Con’t.)

DB Design Strategy Notes Top-down

1) Identify data sets 2) Define data elements

Bottom-up 1) Identify data elements 2) Group them into data sets

Top-Down vs. Bottom-Up

(Con’t.)

Centralized vs. Decentralized Design

Centralized design Typical of simple databases Conducted by single person or small team

Decentralized design Larger numbers of entities and complex

relations Spread across multiple sites Developed by teams (Con’t.)

Centralized Design

(Con’t.)

Decentralized Design

(Con’t.)

Database Management System Oracle Database Server MS SQL Server DB2 MySQL Many more………

(Con’t.)

Most problems are non-technical Poorly selected data Badly organized data Incorrect data models Software has limited capability (oversell) Systems managers underestimate time

requirements Systems can be underutilized Systems can be (and have been) abandoned Personnel problems

(Con’t.)

Bibliographic Reference: Management Information Systems by

Kenneth C Laudon_Jane P Laudon http://predoc.org/download/docs-100865/100865

.doc

http://www.shsu.edu/~csc_tjm/summer2000/cs334/Chapter06/Chapter6.html

THE END !!!!!!