chap dbms database planning

8/8/2019 Chap DBMS Database Planning

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D A T A B A S E P L A N N I N G , D E S I G N ,A N D A DM I N I S T R A T IO N T R A N S P A R EN C I E S

Chapter 9

MTI Faculty of Computer Science UI, 2005


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Chapter 9 - Objectives

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y Main components of an information system.

y Main stages of database system developmentlifecycle.

y Main phases of database design: conceptual,logical, and physical design.

y Benefits of CASE tools.

y How to evaluate and select a DBMS.

2 Pearson Education Limited 1995, 2005


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Information System3

Resources that enable collection, management,

control, and dissemination of information throughout

an organization.

y Database is fundamental component of IS, and its

development/usage should be viewed from perspective

of the wider requirements of the organization.

Pearson Education Limited 1995, 2005


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Database System Development Lifecycle

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y Database planning

y System definition

y Requirements collection

and analysis

y Database design

y DBMS selection (optional)

y Application design

y Prototyping (optional)

y

Implementationy Data conversion and

loading

y Testing

y Operational

maintenance


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Stages of the Database SystemDevelopment Lifecycle

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Database Planning6

y Management activities that allow stagesof database system development lifecycleto be realized as efficiently and

effectively as possible.

y Must be integrated with overall IS strategy of the

organization.



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Database Planning7

y Database planning should also include

development of standards that govern:

how data will be collected,

how the format should be specified,

what necessary documentation will be needed,

how design and implementation should proceed.



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System Definition8

y Describes scope and boundaries of database

system and the major user views.

y User view defines what is required of a databasesystem from perspective of:

a particular job role (such as Manager or Supervisor) or

enterprise application area (such as marketing, personnel,

or stock control).



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System Definition9

y Database application may have one or more user

views.

y Identifying user views helps ensure that no major

users of the database are forgotten when developing

requirements for new system.

y User views also help in development of complex

database system allowing requirements to be brokendown into manageable pieces.



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Representation of a Database System with Multiple

User Views10



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Requirements Collection and Analysis11

y Process of collecting and analyzinginformation about the part oforganization to be supported by the

database system, and using thisinformation to identify usersrequirements of new system.



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y Information is gathered for each major user viewincluding:

a description of data used or generated;

details of how data is to be used/generated; any additional requirements for new database system.

y Information is analyzed to identify requirements tobe included in new database system. Described in the

requirements specification.



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y Another important activity is deciding how to

manage the requirements for a database system

with multiple user views.

y Three main approaches:

centralized approach;

view integration approach;

combination of both approaches.



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y Centralized approach

Requirements for each user view are merged into a single

set of requirements.

A data model is created representing all user views duringthe database design stage.



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Centralized Approach to Managing Multiple

User Views15



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y View integration approach

Requirements for each user view remain as separate lists.

Data models representing each user view are created and

then merged later during the database design stage.



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y Data model representing single user view (or asubset of all user views) is called a local data model.

y Each model includes diagrams and documentation

describing requirements for one or more but notall user views of database.

y Local data models are then merged at a later stageduring database design to produce aglobal data

model, which represents alluser views for thedatabase.



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View Integration Approach to Managing Multiple User

Views18

Pearson Education Limited

1995, 2005


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Database Design19

y Process of creating a design for adatabase that will support theenterprises mission statement andmission objectives for the requireddatabase system.

y Main purposes of data modeling include: to assist in understanding the meaning (semantics) of the

data;

to facilitate communication about the informationrequirements.



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Database Design20

y Building data model requires answering

questions about entities, relationships, and

attributes.

y A data model ensures we understand:- each users perspective of the data;

- nature of the data itself, independent of its physical

representations;

- use of data across user views.



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Criteria to Produce an Optimal Data Model

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Database Design22

y Three phases of database design:

Conceptual database design

Logical database design Physical database design.



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Conceptual Database Design23

y Process of constructing a model of thedata used in an enterprise, independentofallphysical considerations.

y Data model is built using the informationin users requirements specification.

y

Conceptual data model is source ofinformation for logical design phase.



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Logical Database Design24

y Process of constructing a model of thedata used in an enterprise based on aspecific data model (e.g. relational), but

independent of a particular DBMS andother physical considerations.

y Conceptual data model is refined and

mapped on to a logical data model.



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Physical Database Design25

y Process of producing a description of thedatabase implementation on secondarystorage.

y Describes base relations, fileorganizations, and indexes used to achieveefficient access to data. Also describes anyassociated integrity constraints and

secuirty measures.

y Tailored to a specific DBMS system.



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Three-Level ANSI-SPARC Architecture and

Phases of Database Design26



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DBMS Selection27

y Selection of an appropriate DBMS to support thedatabase system.

y Undertaken at any time prior to logical designprovided sufficient information is available

regarding system requirements.y Main steps to selecting a DBMS:

define Terms ofReference of study;

shortlist two or three products;

evaluate products; recommend selection and produce report.



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DBMS Evaluation Features28



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DBMS Evaluation Features29



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Application Design30

y Design of user interface and applicationprograms that use and process thedatabase.

y Database design and application designare parallel activities.

y Includes two important activities: transaction design;

user interface design.



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Application Design - Transactions31

yAn action, or series of actions, carriedout by a single user or applicationprogram, which accesses or changes

content of the database.

y Should define and document the high-level characteristics of the transactions

required.



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Application Design - Transactions32

y Important characteristics oftransactions: data to be used by the transaction;

functional characteristics of the transaction;

output of the transaction;

importance to the users;

expected rate of usage.

y Three main types of transactions:retrieval, update, and mixed.



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Prototyping33

y Building working model of a databasesystem.

y Purpose to identify features of a system that work well, or are

inadequate;

to suggest improvements or even new features;

to clarify the users requirements;

to evaluate feasibility of a particular system design.



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Implementation34

y Physical realization of the database andapplication designs. Use DDL to create database schemas and empty

database files.

Use DDL to create any specified user views.

Use 3GL or 4GL to create the application programs.This will include the database transactionsimplemented using the DML, possibly embedded in ahost programming language.



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Data Conversion and Loading35

y Transferring any existing data into newdatabase and converting any existingapplications to run on new database.

y

Only required when new database system isreplacing an old system. DBMS normally has utility that loads existing files

into new database.

y May be possible to convert and use

application programs from old system for useby new system.



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Testing36

y Process of running the database system withintent of finding errors.

y Use carefully planned test strategies andrealistic data.

y Testing cannot show absence of faults; it canshow only that software faults are present.

y Demonstrates that database and application

programs appearto be working according torequirements.



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Operational Maintenance38

y Process of monitoring and maintainingdatabase system following installation.

y Monitoring performance of system. if performance falls, may require tuning or

reorganization of the database.

y Maintaining and upgrading databaseapplication (when required).

y Incorporating new requirements intodatabase application.



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CASE Tools

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y Support provided by CASE tools include:

- data dictionary to store information about database

systems data;

- design tools to support data analysis;- tools to permit development of corporate data model, and

conceptual and logical data models;

- tools to enable prototyping of applications.



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CASE Tools and Database SystemDevelopment Lifecycle

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