DBMS Chapter 1

Data

Raw Data.

Stored representation of meaningful objects/events. 

Structured: numbers, text, dates.

Unstructured: images, videos, documents

Information

Processed Data. Data processed to increase knowledge of the user.

Metadata

Label. Data that describes the properties & context of user data (field sizes, data types, allowable values, context).

Role of Metadata

Describes the properties/characteristics of data.

Provides context so users understand and interpret data correctly.

Stored in a repository for design, management, and controlled access.

Data Redundancy

Duplicate data wastes space and increases maintenance.

Changes in one file may cause inconsistencies and compromise integrity.

Cost and Risks of Database Approach

Requires specialized personnel.

Installation and management cost and complexity.

Conversion cost from old systems.

Explicit backup & recovery needed.

Possible organizational conflict.

Advantages of Database Approach

Program–data independence.

Planned data redundancy for consistency.

Improved data sharing, consistency, quality, and decision support.

Enforcement of standards.

Reduced maintenance and higher productivity.

Problems in Data Dependency

Each program must maintain its own data and metadata.

Repeated coding for reading, inserting, updating, deleting.

Non-standard file formats and lack of central control.

Enterprise Database Model

First step in database development.

High-level picture of organizational data: entities and relationships.

SDLC (PALPIM)

System Development Life Cycle (SDLC)

Planning – Preliminary understanding; request for study.

Analysis – Requirements analysis; functional specifications.

Logical Design – Design transactions, forms, data integrity/security.

Physical Design – Define database to DBMS, physical organization.

Implementation – Programming, testing, training, installation.

Maintenance – Monitor, repair, enhance.

Prototyping

1. Identify problem

2. Develop initial prototype

3. Implement and use prototype

4. Revise and enhance prototype

5. Convert to operational system