Lecture 2: Database Development Process

ISOM3260, Spring 2014

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Where we are now• Database environment

– introduction to database• Database development process

– steps to develop a database• Conceptual data modeling

– entity-relationship (ER) diagram; enhanced ER• Logical database design

– transforming ER diagram into relations; normalization• Physical database design

– technical specifications of the database• Database implementation

– Structured Query Language (SQL), Advanced SQL• Advanced topics

– data and database administration

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Database Development Process

• Information Systems Architecture• Information Systems Planning• Systems Development Life Cycle• Prototyping• People involved in database development• Three-schema database architecture• Three-tiered database location architecture

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Information Systems Architecture

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Information Systems Architecture• overall blueprint or plan for an organization’s

information systems• developed during IS planning• consists of

– Data (Enterprise Data Model)– Processes (that manipulate data, e.g. data flow diagrams)– Network (data communication topology diagram)– People (perform processes or are source or receiver of data)– Events and points in time (when processes are performed)– Reasons for events and rules (e.g. decision tables)

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Fig. 1-3: Segment from Enterprise Data Model(shows the high-level entities and their relationships)

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Data Flow Diagram

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Network Diagram

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Decision Table

Note: for salaried employees the action stub chosen will always be the same…therefore hours worked is an indifferent condition

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Decision Tree representation of salary decision

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Information Systems Planning

• Align IT with the business strategies of the organization• Three steps:

1. Identify strategic planning factors Organization goals (what we hope to achieve) Critical success factors (what must work in order to meet the goals) Problem areas (what are the current weaknesses)

2. Identify corporate planning objects Organizational units (departments of the organization) Organizational locations (places of operation) Business functions (processes that support the organization’s mission) Entity types (data on people, places, and things managed by the

organization Information systems

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Strategic Planning Factors

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Example: Planning Objects

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Example: Planning Objects (cont.)

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Information Systems Planning (cont.)

3. Develop an enterprise model Functional decomposition of business functions Enterprise data model

– Entity-relationship diagram– Descriptions of entity types– Relationships between entities– Business rules

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Process decomposition of an order fulfillment function (Pine Valley Furniture)

Decomposition -- breaking business functions into smaller tasks in a hierarchical structure chart

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Figure 1-3: Segment from enterprise data model

Enterprise data model describes the entities in an organization and the relationship between these entities

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Approaches to Database Development

• System Development Life Cycle (SDLC)– Detailed, well-planned development process– Time-consuming, but comprehensive– Long development cycle

• Prototyping– Rapid application development (RAD) method– Cursory attempt at conceptual data modeling– Define database during development of initial prototype.– Repeat implementation and maintenance activities with new

prototype versions

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Database development activities during SDLC

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Figure 1-8: Prototyping methodology and database development process

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People Involved in Database Development

• Business analysts/Systems analysts– work with management and users to analyze information

requirements• Database analysts

– concentrate on requirements and design for database• Users

– provide assessment of their information needs• Programmers• Database/Data administrators• Other technical experts

– systems programmers, network administrators, testers, technical writers

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Three Schema Architecture for Database Development

• All views of the same database• Conceptual schema

– technology independent– analysis phase

• External schema– one or more user views– each user view is a subset of conceptual schema– logical design phase

• Internal schema– physical design phase– how data are stored in a computer’s secondary memory

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Three-schema database architecture

External schema

Different people have different views of the database…these are the external schema

Internal schema

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Process of developing three-schema architecture for a database project

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Three-Tiered Database Location Architecture

• Where to store the data during physical database design• Client tier

– presentation tier– desktop or notebook computer manages user interface and

localized data• Application/Web tier

– process services tier– provides access from client tier to data in enterprise tier

• Enterprise tier– data services tier– minicomputer or mainframe manages organization data

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Figure 1-12: Three-tiered client/server database architecture

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Review Questions

• What is an information systems architecture?• What are the 3 steps in information systems planning?• What are the 3 planning factors?• What are the 5 planning objects?• What are the two approaches to database development?• Who are the people involved in database development?• What is the 3-schema database architecture?• What is the 3-tiered database location architecture?