Transcript Elements of Database System

Elements of Database System
In this Chapter we will Examine
• The Relationships among three Elements
•People
•Software
•Technique
And how the database approach may be used to
develop systems that effectively support
organizational needs
How to design and structure effective DB
System
Elements of Database Systems
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Structure:
◦ 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 System
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How 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 site
Land is valuable commodity, so it use is carefully
planned
Data however, may not be recognized as a
valuable resource, and often little planning
The Need for Planning & Modular
Design
Database 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
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The Need for Planning & Modular
Design
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A 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 & Modular
design
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Entity:
◦ 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
Personal Mgmt
module
Personal
database
Marketing module
Mkt database
The Need for Access, Security, &
Adaptability
If a building is poorly designed then is that
easy to access and so on
 Someone may be break the building and
steal something
 If it is constructed then it shouldn’t be so
expensive to put new things init.
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So good Database system design is to
develop a DBMP
DB System Master Plan
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Suggested outline for DBMP
◦ Organizational environment
 Goals and objective
 Organizational structure & function
◦ Elements of the database
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A major entities and relationship
Entity groups
Modules
User groups
Costs and benefits
Implementation schedule
◦ Summary
DBMS consider
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Two 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 Charts
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Purpose 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 institute
course
Instructor
Participant
Evaluation
Prospect
Organization
Entity chart for institute
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Entities of interest were
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Course
Instructors
Participants
Course evaluation
Prospects
And organization for which prospects work
Entity chart
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Relationship in the diagram are of three
types
◦ One-to-one
◦ One-to-many
◦ Many-to-many
Details are as…..
Entity chart
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One 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 chart
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One 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 chart
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Many 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 Groups
Large 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 together
 Structure, relationship and development
of it
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Costs and Benefits
Investment they can pay for DBS
 Cost of development
 Expensive to develop
 Could be uncertainty for cost and time
 Value of the benefits of DBS are more
difficult to estimate than cost
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Thanks very much!!
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Any Questions????????