INF3703 - Chapter 10 Database Development Process

Database Principles 3rd Ed., Coronel, Morris, Crockett, Blewett
©2020 Cengage EMEA
Database Principles
Fundamentals of Design,
Implementation, and Management
Carlos Coronel, Steven Morris,
Keeley Crockett, Craig Blewett
CHAPTER 10
DATABASE DEVELOPMENT
PROCESS

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In this chapter, you will learn:
• That successful database design must reflect
the information system of which the
database is a part
• That successful information systems are
developed within a framework known as the
Systems Development Life Cycle (SDLC)

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In this chapter, you will learn (continued):
• That within the information system, the most
successful databases are subject to frequent
evaluation and revision within a framework
known as the Database Life Cycle (DBLC)
• How to conduct evaluation and revision within
the SDLC and DBLC frameworks
• About database design strategies: top-down
vs. bottom-up design and centralised vs.
decentralised design

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In this chapter, you will learn (continued):
• Common threats to the security of the data
and what security measures could be put in
place
• The importance of the database
administration in an organisation
• The technical and managerial roles of the
database administrator (DBA)

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The Information System
• Provides for data collection, storage, and
retrieval
• Composed of people, hardware, software,
database(s), application programs, and
procedures
• Systems analysis
– Process that establishes need for and extent of
information system
• Systems development
– Process of creating information system

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The Information System (continued)
• Applications
– Transform data into information that forms basis
for decision making
– Usually produce the following:
• Formal report
• Tabulations
• Graphic displays
– Composed of following two parts:
• Data
• Code by which data are transformed into information

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• Information system performance depends on triad of
factors:
– Database design and implementation
– Application design and implementation
– Administrative procedures
• Database development
– Process of database design and implementation
– Primary objective is to create complete, normalised, non-
redundant (to the extent possible), and fully integrated
conceptual, logical, and physical database models

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The Systems Development Life Cycle
(SDLC)
• The Systems Development Life Cycle (SDLC) is
a general framework through which you can
track and come to understand the activities
required to develop and maintain information
systems.
• Provides “big picture” within which database
design and application development can be
mapped out and evaluated

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(SDLC) (continued)
• Divided into following five phases:
– Planning
– Analysis
– Detailed systems design
– Implementation
– Maintenance
• Iterative rather than sequential process

(SDLC) (continued)

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Planning
• Yields general overview of company and its
objectives
• Initial assessment made of information-flow-
and-extent requirements
• Must begin to study and evaluate alternate
solutions
– Technical aspects of hardware and software
requirements
– System cost

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Analysis
• Problems defined during planning phase are
examined in greater detail during analysis
• Thorough audit of user requirements
• Existing hardware and software systems are
studied
• Goal is better understanding of system’s
functional areas, actual and potential
problems, and opportunities

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Analysis (continued)
• Includes creation of logical system design
– Must specify appropriate conceptual data model, inputs,
processes, and expected output requirements
– Might use tools such as data flow diagrams (DFDs),
hierarchical input process output (HIPO) diagrams, and
entity relationship (ER) diagrams
– Yields functional descriptions of system’s components
(modules) for each process within database environment

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Detailed Systems Design
• Designer completes design of system’s
processes
• Includes all necessary technical specifications
• Steps are laid out for conversion from old to
new system
• Training principles and methodologies are also
planned

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Implementation
• Hardware, DBMS software, and application
programs are installed, and database design is
implemented
• Cycle of coding, testing, and debugging
continues until database is ready to be
delivered
• Database is created and system is customised
by creation of tables and views, and user
authorisations

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Maintenance
• Maintenance activities group into three types:
– Corrective maintenance in response to systems errors
– Adaptive maintenance due to changes in business environment
– Perfective maintenance to enhance system
• Computer-assisted systems engineering
– Make it possible to produce better systems within reasonable
amount of time and at reasonable cost

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The Database Life Cycle (DBLC)

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The Database Initial Study
• Overall purpose:
– Analyse company situation
– Define problems and constraints
– Define objectives
– Define scope and boundaries
• Interactive and iterative processes required to
complete first phase of DBLC successfully

The Database Initial Study (continued)

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Analyse the Company Situation
• Analysis–To break up any whole into its parts so as to find
out their nature, function, and so on
• Company situation
– General conditions in which company operates, its
organisational structure, and its mission
• Analyse company situation
– Discover what company’s operational components are, how
they function, and how they interact

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Define Problems and Constraints
• Managerial view of company’s operation is often
different from that of end users
• Designer must continue to carefully probe to generate
additional information that will help define problems
within larger framework of company operations
• Finding precise answers is important
• Defining problems does not always lead to perfect
solution

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Define Objectives
• Designer must ensure that database system objectives
correspond to those envisioned by end user(s)
• Designer must begin to address following questions:
– What is proposed system’s initial objective?
– Will system interface with other existing or future systems in the
company?
– Will system share data with other systems or users?

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Define Scope and Boundaries
• Scope
– Defines extent of design according to operational requirements
– Helps define required data structures, type and number of
entities, and physical size of database
• Boundaries
– Limits external to system
– Often imposed by existing hardware and software

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Database Design
• Necessary to concentrate on data
• Characteristics required to build database
model
• Two views of data within system:
– Business view of data as information source
– Designer’s view of data structure, its access, and
activities required to transform data into
information

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Database Design (continued)
• Loosely related to analysis and design of larger system
• Systems analysts or systems programmers are in charge of
designing other system components
– Their activities create procedures that will help transform data within
database into useful information
• Does not constitute sequential process
– Iterative process that provides continuous feedback designed to trace
previous steps

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Database Design (continued)

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I. Conceptual Design Overview
• Data modeling used to create an abstract
database structure that represents real-world
objects in most realistic way possible
• Must embody clear understanding of business
and its functional areas
• Ensure that all data needed are in model, and
that all data in model are needed

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I. Conceptual Design Overview
(continued)
• Requires four steps
– Data analysis and requirements
– Entity relationship modeling and normalisation
– Data model verification
– Distributed database design

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II. DBMS Software Selection
• Critical to information system’s smooth
operation
• Advantages and disadvantages should be
carefully studied
• Factors affecting purchasing decisions include:
– Cost, DBMS Features and Tools, underlying Model,
Portability and Hard ware requirements.

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III. Logical Design Overview
• Used to translate conceptual design into
internal model for selected database
management system
• Logical design is software-dependent
• Requires that all objects in model be
mapped to specific constructs used by
selected database software

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(continued)
The logical design stage consists of the
following phases:
1. Creating the logical data model.
2. Validating the logical data model using
normalisation.

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(continued)
4. Assigning and validating integrity
constraints.
5. Merging logical models constructed for
different parts for the database together.
6. Reviewing the logical data model with the
use

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IV. Physical Design Overview
• Process of selecting data storage and data access
characteristics of database
• Storage characteristics are function of device types supported
by hardware, type of data access methods supported by
system, and DBMS
• Particularly important in older hierarchical and network
models
• Becomes more complex when data are distributed at different
locations

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(continued)
Physical database design can be broken down
into a number of stages:
1. Analyse data volume and database usage.
2. Translate each relation identified in the logical
data model into tables.
3. Determine a suitable file organisation.

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(continued)
4. Define indexes.
5. Define user views.
6. Estimate data storage requirements.
7. Determine database security for users.

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Implementation and Loading
• New database implementation requires
creation of special storage-related constructs
to house end-user tables

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Implementation and Loading (continued)

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Performance
• One of most important factors in certain
database implementations
• Not all DBMSs have performance-monitoring
and fine-tuning tools embedded in their
software
• There is no standard measurement for
database performance
• Not only (nor even main) factor

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Backup and Recovery
• Database can be subject to data loss through
unintended data deletion and power outages
• Data backup and recovery procedures
– Create safety valve
• Allow database administrator to ensure availability of
consistent data

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Integrity
• Enforced through proper use of primary and
foreign key rules

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Database Security
• Data must be protected from access by unauthorised users
• Establish security goals
– What are we trying to protect the database from?
– What security related problems are we trying to prevent?
• The most common security goals relate to the integrity,
confidentiality and the availability of data.

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Threats to Security
• Threats are any set of circumstances that have
the potential to cause loss, misuse or harm to
the system and/or its data.
• Threats can cause:
• The loss of the integrity of data through
unauthorised modification.
– For example a person gaining unauthorised access
to a bank account and removing some money
from the account.

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Threats to Security
• The loss of availability of the data.
– For example some adversary causes the database system from being
operational which stops authorised users of the data from accessing it.
• The loss of confidentiality of the data (also referred to as the
privacy of data).
– This could be caused by a person gaining access to private information
such as a password or a bank account balance.

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Examples of Threats
• Theft and fraud of data.
• Human error which causes accidental loss of
data.
• Electronic infections
– Viruses
– Email Viruses
– Worms
– Trojan Horses

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Examples of Threats (continued)
• The occurrence of natural disasters such as
hurricanes, fires or floods.
• Unauthorised access and modification of data.
• Employee sabotage is concerned with the
deliberate acts of malice against the
organisation.
• Poor database administration.

Examples of Threats (continued)

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Data Security Measures
• Physical security allows only authorised
personnel physical access to specific areas.
• User authentication is a way of identifying the
user and verifying that the user is allowed to
access some restricted data or application.
– achieved through the use of passwords and access
rights.
• Audit trails are usually provided by the DBMS
to check for access violations.

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Data Security Measures (continued)
• Data encryption
– Aim for Zero Trust Policy
• User-defined policies and procedures
• Backup and recovery strategies
• Antivirus software
• Firewalls

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Testing and Evaluation
• Occurs in parallel with applications programming
• Database tools used to prototype applications
• If implementation fails to meet some of system’s
evaluation criteria:
– Fine-tune specific system and DBMS configuration parameters
– Modify physical design
– Modify logical design
– Upgrade or change DBMS software and/or hardware platform

Common Sources for Database Failure

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Database Backups
• Database backups can be performed at
different levels:
– Full backup or dump
– Differential backup
– Transaction log backup

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Database Recovery
• The type and extent of the required recovery are
first determined
• If the entire database needs to be recovered to a
consistent state, the recovery uses the most
recent backup copy of the database in a known
consistent state.
• If the database needs to be recovered but the
committed portion of the database is still usable,
the recovery process uses the transaction log to
‘undo’ all of the transactions that were not
committed

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Operation
• Once database has passed evaluation stage, it
is considered operational
• Beginning of operational phase starts process
of system evolution

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Maintenance and Evolution
• Required periodic maintenance:
– Preventive maintenance (backup)
– Corrective maintenance (recovery)
– Adaptive maintenance
– Assignment of access permissions and their
maintenance for new and old users
– Generation of database access statistics
– Periodic security audits
– Periodic system-usage summaries

Parallel Activities in the DBLC and the
SDLC

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Database Design Strategies
Two classical approaches to database design:
– Top-down design
• Identifies data sets
• Defines data elements for each of those sets
– Bottom-up design
• Identifies data elements (items)
• Groups them together in data sets

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Database Design Strategies
Top-down vs. bottom-up design sequencing

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Centralised vs. Decentralised Design
• Database design may be based on two very different
design philosophies:
– Centralised design
• Productive when data component is composed of
relatively small number of objects and procedures
– Decentralised design
• Used when data component of system has considerable
number of entities and complex relations on which very
complex operations are performed

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Centralised Design

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(continued)
• Aggregation process
– Requires designer to create single model in which
various aggregation problems must be addressed:
• Synonyms and homonyms
• Entity and entity subtypes
• Conflicting object definitions

Summary of aggregation problems

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Database Administration
• Data management is a complex job
• Led to the development of the database
administration function.
• The person responsible for the control of
thecentralised and shared database is the
database administrator (DBA).

The placement of the DBA function

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DBA Activities
• Database planning, including the definition of
standards, procedures and enforcement.
• Database requirements gathering and
conceptual design.
• Database logical design and transaction
design.

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DBA Activities (continued)
• Database physical design and implementation.
• Database testing and debugging.
• Database operations and maintenance,
including installation, conversion and
migration.
• Database training and support.

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(continued)
• End-User Support
– Gathering user requirements
– Building end-user confidence.
– Resolving conflicts and problems.
– Finding solutions to information needs.
– Ensuring quality and integrity of applications
and data.
– Managing the training and support of DBMS
users.

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(continued)
• Policies, Procedures and Standards
– Policies are general statements of direction or
action that communicate and support DBA goals.
– Standards are more detailed and specific than
policies and describe the minimum requirements
of a given DBA activity.
– Procedures are written instructions that describe
a series of steps to be followed during the
performance of a given activity.

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(continued)
• Data Security, Privacy and Integrity
– Protecting the security and privacy of the data in
the database is a function of authorisation
management.
– Authorisation management defines procedures to
protect and guarantee database security and
integrity.
– Includes: user access management, view
definition, DBMS access control and DBMS usage
monitoring.

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(continued)
• Data Backup and Recovery
– Many DBA departments have created a position staffed by the
database security officer (DSO).
– The DSO’s activities are often classified as disaster management.
– Disaster management includes all of the DBA activities designed to
secure data availability following a physical disaster or a database
integrity failure.
– Disaster management includes all planning, organising and testing of
database contingency plans and recovery procedures.

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(continued)
• Data Distribution and Use
– The DBA is responsible for ensuring that the data
are distributed to the right people, at the right
time and in the right format.

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The Technical Role of the DBA
• Evaluating, selecting and installing the DBMS and related
utilities.
• Designing and implementing databases and applications.
• Testing and evaluating databases and applications.
• Operating the DBMS, utilities and applications.
• Training and supporting users.
• Maintaining the DBMS, utilities and applications.

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Evaluating, Selecting and Installing the
DBMS and Utilities (DBA)
• Covers the selection of the database
management system, utility software and
supporting hardware for use in the
organisation.
• Must be based primarily on the organisation’s
needs
• The DBA would be wise to develop a checklist
of desired DBMS features.

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Designing and Implementing
Databases and Applications (DBA)
• Covers data modelling and design services to
the end-user community
• Determine and enforce standards and
procedures to be used.
• DBA then provides the necessary assistance
and support during the design of the database
at the conceptual, logical and physical levels

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Testing and Evaluating Databases and
Applications (DBA)
• The DBA must also provide testing and evaluation services for
all of the database and end-user applications.
• Those services are the logical extension of the design,
development and implementation services.
• Testing procedures and standards must already be in place
before any application program can be approved for use in
the company.

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Operating the DBMS, Utilities and
Applications
(DBA)
• DBMS operations can be divided into four
main areas:
– System support.
– Performance monitoring and tuning.
– Backup and recovery.
– Security auditing and monitoring.

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Training and Supporting Users (DBA)
• Training people to use the DBMS and its tools
is included in the DBA’s technical activities.
• The DBA also provides or secures technical
training in the use of the DBMS and its utilities
for the applications programmers.

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Maintaining the DBMS, Utilities and
Applications (DBA)
• The maintenance activities of the DBA are an
extension of the operational activities.
• Maintenance activities are dedicated to the
preservation of the DBMS environment.

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Developing a Data
Administration Strategy
• Critical step for any organisation is to ensure
its information system supports strategic plans
for each of the company’s business areas
• Database administration strategy must not
conflict with information systems plans

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Developing a Database
Administration Strategy (continued)
• Information engineering
– Translates strategic company’s strategic goals into
data and applications that will help company
achieve those goals
– Output of IE process is information systems
architecture that serves as basis for planning,
development, and control of future information
systems

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Summary
• Information system is designed to facilitate
transformation of data into information and to
manage both data and information
• SDLC traces history (life cycle) of an
application within the information system

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Summary (continued)
• DBLC describes history of database within the
information system
• Database design and implementation process
moves through series of well-defined stages
• Conceptual portion of design may be subject
to several variations, based on two design
philosophies

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Summary (continued)
• Threats to database security include the loss
of integrity, confidentiality and availability of
data.
• The database administrator (DBA) is
responsible for managing the corporate
database.
• The development of the data administration
strategy is closely related to the company’s
mission and objectives.

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Summary (continued)
• The DA and the DBA functions tend to overlap.
• The managerial services of the DBA function
include at least:
– Supporting the end-user community
– Defining and enforcing policies, procedures and
standards for the database function
– Ensuring data security, privacy and integrity
– Providing data backup and recovery services
– Monitoring the distribution and use of the data in the
database

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Summary (continued)
• The technical role requires the DBA to be
involved in at least these activities:
– Evaluating, selecting and installing the DBMS
– Designing and implementing databases and
applications
– Testing and evaluating databases and applications
– Operating the DBMS, utilities and applications
– Training and supporting users
– Maintaining the DBMS, utilities and applications

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