Elements of Database Elements of Database SystemSystem

In this Chapter we will Examine• The Relationships among three Elements•People•Software•TechniqueAnd how the database approach may be used to develop systems that effectively support organizational needsHow to design and structure effective DB System

Elements of Database Elements of Database SystemsSystemsStructure:

◦Refer to the parts of system and how these part interact

◦The concern is with blending the five elements into a database system that serve the need of the organization.

After this chapter you should understand how hardware, software, people, procedures, and plans can be blended to form an effective database system

Elements of Database Elements of Database SystemSystemHow a Database System is like a

Campus◦When campus or new building is planned◦This plan takes into consideration ◦The special needs◦The special characteristics of the siteLand is valuable commodity, so it use is

carefully plannedData however, may not be recognized as

a valuable resource, and often little planning

The Need for Planning & The Need for Planning & Modular DesignModular DesignDatabase should be compatible

with all organizational units. Because this can lead to expensive

redundancy and difficult to maintain

Think about a building; links between building walls, and whole structure.

And they serve the need of the community

The Need for Planning & The Need for Planning & Modular DesignModular DesignA well designed database system

consist of◦Modules

Is used to describe a major element of the overall database system. DBS are loosely coupled and may be built independently, but they should fit into a grander scheme described in DB Master plan.

DBSMP lays out the ultimate structure and contents of the database system

◦Subsystems Of a database system contain data about

entities, such as customers and products

The need for planning & The need for planning & Modular designModular designEntity:

◦Is any object, tangible, or intangible, about which the organization wishes to store data.

◦Entities have attributes such as name, color, price

◦Entities and attributes must be accessible through some way

◦The way is called navigation path;◦Arrows in database are pointers

indicating where the programe should look on the system’s storage device to find record

Database system

Marketing module

Personal Mgmt module

Personal database

Mkt database

The Need for Access, The Need for Access, Security, & AdaptabilitySecurity, & AdaptabilityIf a building is poorly designed then

is that easy to access and so onSomeone may be break the building

and steal somethingIf it is constructed then it shouldn’t

be so expensive to put new things init.

So good Database system design is to develop a DBMP

DB System Master PlanDB System Master PlanSuggested outline for DBMP

◦Organizational environment Goals and objective Organizational structure & function

◦Elements of the database A major entities and relationship Entity groups Modules User groups Costs and benefits Implementation schedule

◦Summary

DBMS considerDBMS considerTwo aspects are important

◦Organizational goals and objective◦The manner in which the enterprise

is structured Assist the managers of organizations in

measuring the level of goal attainment and in steering the organization towards its goals

Entity ChartsEntity ChartsPurpose of DBMSMP is to guide

◦Organization to manage its information resources effectively.

Information needs at every level of organization

◦It should identify the major information users and their needs.

◦It should specify the entities to be contained in DB and relation between them.

◦Specified entities and relationships can be illustrated in diagram

Entity Chart for instituteEntity Chart for institute

course

Evaluation

Instructor

Participant

Organization

Prospect

Entity chart for instituteEntity chart for instituteEntities of interest were

◦Course◦Instructors◦Participants◦Course evaluation◦Prospects◦And organization for which prospects

work

Entity chartEntity chartRelationship in the diagram are

of three types◦One-to-one◦One-to-many◦Many-to-many

Details are as…..

Entity chartEntity chartOne to one

◦One instance of an entity of a given type is associated with only one member of another type; such as, a participant in a course fills out one evaluation form for the course. Conversely, a given evaluation form was prepared by one participant

Entity chartEntity chartOne to many

◦One instance of a given type of entity is related to many instance of another type. Such as; one prospects work for one organization, so the line emanating from prospect has a single arrowhead where it terminates with organization. But one organization may have several prospects for a given course.

Entity chartEntity chartMany to many

◦Relationship is one in which many entities for one type are associated with many instance of another type. Such as, an instructor may teach many different courses, and one course may be taught by many different instructors.

Entity GroupsEntity GroupsLarge and complex DBS; can not be

designed and build at once. So it should be done piece by piece. The Master plan should describe the

major pieces and or modules of the system to be developed

How they will work togetherStructure, relationship and

development of it

Costs and BenefitsCosts and BenefitsInvestment they can pay for DBSCost of developmentExpensive to developCould be uncertainty for cost and

timeValue of the benefits of DBS are

more difficult to estimate than cost

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