The Database Environmentand Development Process

An Overview

Outline

Basic concepts and definitions Benefits of Database Management

Systems (DBMS) A brief look at the Relational DBMS Types of Database Applications Database Development Process

Basic Concepts and Definitions

Database An organized collection of logically related data

a list of clients, or customer orders organized in a way that enables fast and efficient

storage, access and manipulation Data

Facts that can be recorded and stored using computer media traditionally this included text and numbers modern usage now includes objects such as sounds,

images, and video clips

Database System

The application of technology to business processes, gathering data and creating information that is valuable to managers who make decisions

N. Caroline Daniels, IT: The Management Challenge

A model of an enterprise that captures the information structure and content which describes and operationalizes the function of the enterprise.

Les Waguespack

Information

Data that has been processed in such a way that it can increase the knowledge of the person who uses it

Examples are data that has been: placed in a context (see next slide) summarized (e.g., as in a graph)

Raw Data

How to interpret this?

Metadata

Data that describes the properties or characteristics of other data (a means of providing context for data)

See Table 1-1in textbook

Figure 1-1a Data in Context

Even when the context is provided, large volume of facts is difficult to analyze or make decisions based on.

……………

Figure 1-1b Summarized data

Outline

Basic concepts and definitions Benefits of Database Management

Systems (DBMS) A brief look at the Relational DBMS Types of Database Applications Database Development Process

Traditional File Processing

Date back to before we had databases Still in use today, including backup of

database systems

Disadvantages of File Processing

Program-Data Dependence All programs maintain metadata for each file they use

Data Redundancy (Duplication of data) Different systems/programs have separate copies of the same

data

Limited Data Sharing No centralized control of data

Lengthy Development Times Programmers must design their own file formats

Excessive Program Maintenance 80% of of information systems budget

Problems with Data Redundancy

Waste of space to have duplicate data Causes more maintenance headaches The biggest Problem:

When data changes in one file, could cause inconsistencies

Compromises data integrity

Solution: The DATABASE Approach

Central repository of shared data Data is managed by a controlling agent

(DBMS) Stored in a standardized, convenient

form

Requires a Database Management System (DBMS)

Database Management System

DBMS manages data resources like an operating system manages hardware resources

DBMSDBMS Databasecontainingcentralized

shared data

Application#1

Application#2

Application#3

Database Management Systems (DBMS)

DBMS: General-purpose software system which permits data to

be stored non-redundantly and facilitates the processes of defining, creating, using and maintaining databases

Database and Repository: Includes data and metadata that describes the database

data - the actual values of interestmetadata - descriptions of the characteristics of the stored data

Data and metadata are stored in one place, outside of the application program (decoupled from the code).

Advantages of Database Approach

Program-Data Independence Metadata stored in DBMS, so applications don’t need to

worry about data formats Data queries/updates managed by DBMS so programs

don’t need to process data access routines Results in: increased application development and

maintenance productivity

Minimal Data Redundancy Leads to increased data integrity/consistency

Advantages of Database Approach

Improved Data Sharing Different users get different views of the data

Enforcement of Standards All data access is done in the same way

Improved Data Quality Constraints, data validation rules

Better Data Accessibility/ Responsiveness Use of standard data query language (SQL)

Security, Backup/Recovery, Concurrency Disaster recovery is easier

Costs and Risks of the Database Approach

Up-front costs: Installation Management Cost and Complexity Conversion Costs

Ongoing Costs Requires New, Specialized Personnel Need for Explicit Backup and Recovery

Organizational Conflict Old habits die hard

Evolution of DB Systems Flat files - 1960s - 1980s Hierarchical – 1970s - 1990s Network – 1970s - 1990s Relational – 1980s - present Object-oriented – 1990s - present Object-relational – 1990s - present Data warehousing – 1980s -

present Web-enabled – 1990s - present

Outline

Basic concepts and definitions Benefits of Database Management

Systems (DBMS) A brief look at the Relational DBMS Types of Database Applications Database Development Process

Relational Databases Organize Data in Tables

Field 1 Field 2 Field 3

Record 1Record 2Record 3

Each column represents a Field (a.k.a attribute, characteristic)

Each row represents a Record (a.k.a instance, tuple)

May seem simple, but…

Example: poorly designed database.The purpose of this table is to keep track of students, their majors, advisors and their email addresses.

ST_ID ST_FIRST ST_LAST ST_MAJOR ADV_FIRST ADV_LAST ADV_EMAIL ADV_ID

001 Adam Gopnik Literature William Shakespeare ws@lu.ac.uk 352

035 Sandra Smith Literature James Joyce jj@dbl.edu 465

735 Barbara Richards Astronomy Galileo Galilei gg@pdv.it 773

136 Preston Jones Astronomy Galileo Galilei gg@pdv.it 644

001 Ryan Cooper Literature William Shakespeare ws@lu.ac.uk 352

Consider what would happen when the table has to be updated to reflect the following events:

1.Sandra Smith graduates.2.Galilei’s email has changed3.A new professor is hired and has to be assigned an ID but has not yet been assigned any

students to advise.

The Database Design Process

Conceptual Database Design Entity-Relationship Diagrams (ERDs)

Logical Database Design Translate the conceptual model into files, tables, or

objects (depending on type of DBMS)

Physical Database Design Lay out the actual DBMS architecture

Figure 1-3 Conceptual data model (ERD)

Figure 1-3 Segment from enterprise data model

One customer may place many orders, but each order is placed by a single customer

One-to-many relationship

Figure 1-3 Segment from enterprise data model

One order has many order lines; each order line is associated with a single order

One-to-many relationship

Figure 1-3 Segment from enterprise data model

One product can be in many order lines, each order line refers to a single product

One-to-many relationship

Figure 1-4 Order, Order_Line, Customer, and Product tables

Relationships established in special columns (or tables) that provide links between tables representing the entities.

Data Tables (Relations)

Relationships

Outline

Basic concepts and definitions Benefits of Database Management

Systems (DBMS) A brief look at the Relational DBMS Types of Database Applications Database Development Process

The Range ofDatabase Applications

Personal Database – standalone desktop database Workgroup Database – local area network (<25 users) Department Database – local area network (25-100

users) Enterprise Database – wide-area network (hundreds or

thousands of users)

Components of the Database Environment

CASE Tools – Computer-Aided Software Engineering tools

Database Management System (DBMS) – software for managing the database Database – storehouse of the data Repository – centralized storehouse of metadata

Application Programs – software using the data User Interface – text and graphical displays to users

Human Resources Needed

Systems Analysts Database Analysts/Designers Data/Database Administrators Programmers

Database Responsibilities

Responsibilities Data planning for the

long term Define standards Conceptual and logical

design (ERDs and LDMs)

Physical design Data integrity and

working with other departments

Responsibilities Data security Database performance Backup/recovery Business rules Determine user

requirements (interviewing users)

Design database applications

Program database applications

Outline

Basic concepts and definitions Benefits of Database Management

Systems (DBMS) A brief look at the Relational DBMS Types of Database Applications Database Development within IS

Development Process

Information Systems Architecture

“A conceptual blueprint or plan

that expresses the desired future

structure for the information

systems in an organization.”

Information Systems Architecture

Key components: data processes which manipulate data network which transports data people who perform processes and send and receive

data events and points in time when processes are

performed reasons for events and rules which govern data

processing

Information Engineering

“An Information Systems Architecture is

developed by IS planners following a

particular methodology such as Information

Engineering.”

Information Engineering

A data-oriented methodology to create and maintain information systems

Uses top-down planning in which specific information systems are deduced from a broad understanding of organizational information needs, rather than relying on specific user information requests

Offers perspective on relationship of information systems to business objectives

Top-Down vs. Bottom-Up

Top-Down Planning:

“A methodology that attempts to gain a broad understanding of the information system needs of the entire organization”

Bottom-Up Planning:

“A methodology that identifies and defines IS development projects based upon solving operational business problems or taking advantage of business opportunities”

Information Engineering Planning

Identify strategic planning factors Goals Critical success factors Problem areas

Identify corporate planning objects Organizational units Locations Business functions Entity types

Develop enterprise model Process

decomposition Enterprise data

model (e.g., ERD)

Figure 2.2 -- Example of process decomposition of an order fulfillment function (Pine Valley Furniture)

Decomposition -- breaking large tasks into smaller tasks in a hierarchical structure chart

Enterprise Data Modeling

“The first step in database development, in which the scope and

general contents of organizational databases are

specified.”

Enterprise Data Model

A model which includes: overall range of organizational databases general contents of organizational databases

Built as part of IS planning for the organization and not the design of a particular database

One part of an organization’s overall information systems architecture (ISA)

Figure 2-1 Segment from enterprise data model (Pine Valley Furniture Company) [simplified E-R diagram, repeat of figure 1.3]

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

Example business function-to-data entity matrix (fig. 2.3)

Business Planning X X X XProduct Development X X X XMaterials Management X X X X X XOrder Fulfillment X X X X X X X X XOrder Shipment X X X X X XSales Summarization X X X X XProduction Operations X X X X X X XFinance and Accounting X X X X X X X X

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BusinessFunction (users)

Data Entity Types

Alternative Approaches to Database and IS Development

SDLC System Development Life cycle Detailed, well-planned development process Time-consuming, but comprehensive Long development cycle

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

prototype versions. Especially useful for extending the IS functionality.

Systems Development Life Cycle (SDLC) (figures 2.4, 2.5)

Project Identification and Selection

Project Initiation and Planning

Analysis

Physical Design

Implementation

Maintenance

Logical Design

Database development within SDLC

Identify Project

Initiate and Plan

Analyze

Logical Design

Physical Design

Implementation

Maintenance

EnterpriseData Modeling

ConceptualData Modeling

LogicalDB Design

Physical DBDesign/Creation

DBImplementation

DBMaintenance

Database Development Activities

SDLC

EnterpriseModeling

ConceptualData Modeling

LogicalDB Design

Physical DBDesign/Creation

DBImplementation

DBMaintenance

Enterprise Data Model First step in database development Specifies scope and general content Overall picture of organizational data,

not specific design Entity-relationship diagram

Descriptions of entity types Relationships between entities Business rules

Determine user requirements Determine business rules Build conceptual data model

outcome is an entity-relationship

diagram or similar communication

tool

Conceptual Database Modeling

EnterpriseModeling

ConceptualData Modeling

LogicalDB Design

Physical DBDesign/Creation

DBImplementation

DBMaintenance

Logical Database Design

Select logical database model

Map Entity-Relationship Diagrams

Normalize data structures

Specify business rules

EnterpriseModeling

ConceptualData Modeling

LogicalDB Design

Physical DBDesign/Creation

DBImplementation

DBMaintenance

Physical Database Design

Select DBMS Select storage devices Determine access methods Design files and indexes Determine database distribution Specify update strategies

EnterpriseModeling

ConceptualData Modeling

LogicalDB Design

Physical DBDesign/Creation

DBImplementation

DBMaintenance

The Prototyping Approach

Identify User Needs

Develop Prototype

Evaluate Prototype

Prototype Acceptable?

Implement Prototype

Rev ise