Week 7 Database Development Process

The Database
Development Process
Jaime E Fuentes M.Ed.T.

Learning Objectives
1. List and describe nine components of a typical database
environment.
2. Identify the Database Development Process.
3. Explain the prototyping and agile-development
approaches to database and application development.
4. Explain the differences among external, conceptual, and
internal schemas and the reasons for the Three-
Schema architecture for database development.
5. Explain the roles of the people involved in Database
Development.
2

Software Depression
The Database Environment and
Development Process

4
Software Depression
 Last few decades have seen proliferation of software
applications, many requiring constant maintenance
involving:
correcting faults,
implementing new user requirements,
modifying software to run on new or upgraded
platforms.
 Effort spent on maintenance began to absorb resources at
an alarming rate.

5
Software Depression
As a result, many major software projects were
late,
over budget,
unreliable,
difficult to maintain,
performed poorly.
In late 1960s, led to ‘software crisis’, now refer to
as the ‘software depression’.
Software Depression

6
Software Depression
Major reasons for failure of software projects
includes:
- lack of a complete requirements specification;
- lack of appropriate development methodology;
- poor decomposition of design into manageable
components.
Structured approach to development was proposed
called Information Systems Lifecycle (ISLC).
Software Depression

Information Systems…
Development Process

8
Information System
Resources that enable collection, management,
control, and dissemination of information
throughout an organization.
Database is fundamental component of IS, and its
development/usage should be viewed from
perspective of the wider requirements of the
organization.

Architecture example
CIM
EDI
External
database
access
Business
Operations
Customers
& Suppliers
External
Events
Data
validation
and
retention
Integrated
data warehouse
Access
analysis and
presentation
tools
Information
delivery system
Dialogue
Decision makers
Customers, Suppliers

A more sophisticated example...

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 System Architecture

Components of the Database
Environment
Development Process

13
Components of the Database Environment

Database Development Process
Development Process

Database Development Process
 How do organizations start developing a database?
 In many organizations, database development begins with
enterprise data modeling, which establishes the range
and general contents of organizational databases.
 Its purpose is to create an overall picture or explanation of
organizational data, not the design for a particular
database.
 A particular database provides the data for one or more
information systems, whereas an enterprise data model,
which may encompass many databases, describes the
scope of data maintained by the organization.
 In enterprise data modeling, you review current
systems, analyze the nature of the business areas to be
supported, describe the data needed at a very high level of

Database System Development Lifecycle
Database planning
System definition
Requirements collection and analysis
Database design
DBMS selection (optional)

18
Application design
Prototyping (optional)
Implementation
Data conversion and loading
Testing
Operational maintenance

19
Stages of the Database System Development
Lifecycle

20
Database Planning
Management activities that allow stages of
database system development lifecycle to be
realized as efficiently and effectively as possible.
Must be integrated with overall IS strategy of the
organization.

21
Database Planning – Mission Statement
Mission statement for the database project defines
major aims of database application.
Those driving database project normally define the
mission statement.
Mission statement helps clarify purpose of the
database project and provides clearer path towards
the efficient and effective creation of required
database system.

22
Database Planning – Mission Objectives
Once mission statement is defined, mission
objectives are defined.
Each objective should identify a particular task that
the database must support.
May be accompanied by some additional
information that specifies the work to be done, the
resources with which to do it, and the money to
pay for it all.

23
Database Planning
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.

24
System Definition
Describes scope and boundaries of database system
and the major user views.
User view defines what is required of a database
system from perspective of:
 a particular job role (such as Manager or
Supervisor) or
enterprise application area (such as marketing,
personnel, or stock control).

25
System Definition
Database application may have one or more user
views.
Identifying user views helps ensure that no major
users of the database are forgotten when
developing requirements for new system.
User views also help in development of complex
database system allowing requirements to be
broken down into manageable pieces.
System Definition

26
Representation of a Database System with
Multiple User Views

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Requirements Collection and Analysis
 Process of collecting and analysing information about the part of organization
to be supported by the database system, and using this information to identify
users’ requirements of new system.
 Information is gathered for each major user view including:
 a description of data used or generated;
 details of how data is to be used/generated;
 any additional requirements for new database system.
 Information is analyzed to identify requirements to be included in new database
system. Described in the requirements specification.
 Another important activity is deciding how to manage the requirements for a
database system with multiple user views.
 Three main approaches:
 centralized approach;
 view integration approach;
 combination of both approaches.

28
Centralized approach
Requirements for each user view are merged into
a single set of requirements.
A data model is created representing all user
views during the database design stage.

29
Centralized Approach to Managing Multiple
User Views

30
 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.
 Data model representing single user view (or a subset of all user
views) is called a local data model.
 Each model includes diagrams and documentation describing
requirements for one or more but not all user views of database.
 Local data models are then merged at a later stage during database
design to produce a global data model, which represents all user
views for the database.

31
View Integration Approach to Managing
Multiple User Views

32
Database Design
 Process of creating a design for a database that will support the enterprise’s
mission statement and mission objectives for the required database system.
 Main approaches include:
 Top-down
 Bottom-up
 Inside-out
 Mixed
 Main purposes of data modeling include:
 to assist in understanding the meaning (semantics) of the data;
 to facilitate communication about the information requirements.
 Building data model requires answering questions about entities, relationships,
and attributes.
 A data model ensures we understand:
- each user’s perspective of the data;
- nature of the data itself, independent of its physical representations;
- use of data across user views.

33
Criteria to Produce an Optimal Data Model

34
Database Design
Three phases of database design:
Conceptual database design
Logical database design
Physical database design.

35
Conceptual Database Design
Process of constructing a model of the data used in
an enterprise, independent of all physical
considerations.
Data model is built using the information in users’
requirements specification.
Conceptual data model is source of information for
logical design phase.

36
Logical Database Design
Process of constructing a model of the data
used in an enterprise based on a specific data
model (e.g. relational), but independent of a
particular DBMS and other physical
considerations.
Conceptual data model is refined and mapped
on to a logical data model.

37
Physical Database Design
Process of producing a description of the
database implementation on secondary storage.
Describes base relations, file organizations, and
indexes used to achieve efficient access to
data. Also describes any associated integrity
constraints and secuirty measures.
Tailored to a specific DBMS system.

38
Three-Level ANSI-SPARC Architecture
and Phases of Database Design

39
DBMS Selection
Selection of an appropriate DBMS to support the
database system.
Undertaken at any time prior to logical design
provided sufficient information is available
regarding system requirements.
Main steps to selecting a DBMS:
define Terms of Reference of study;
shortlist two or three products;
evaluate products;
recommend selection and produce report.

40
DBMS Evaluation Features
Pearson Education © 2009

41

42
Example - Evaluation of DBMS Product

43
Application Design
Design of user interface and application
programs that use and process the
database.
Database design and application design are
parallel activities.
Includes two important activities:
transaction design;
user interface design.

44
Application Design - Transactions
An action, or series of actions, carried out by a
single user or application program, which
accesses or changes content of the database.
Should define and document the high-level
characteristics of the transactions required.

45
Important characteristics of transactions:
data to be used by the transaction;
functional characteristics of the transaction;
output of the transaction;
importance to the users;
expected rate of usage.
Three main types of transactions: retrieval,
update, and mixed.

46
Prototyping
Building working model of a database system.
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.

47
Implementation
Physical realization of the database and
application 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
transactions implemented using the DML,
possibly embedded in a host programming
language.

48
Data Conversion and Loading
Transferring any existing data into new database
and converting any existing applications to run on
new database.
Only required when new database system is
replacing an old system.
DBMS normally has utility that loads existing files
into new database.
May be possible to convert and use application
programs from old system for use by new system.

49
Testing
Process of running the database system with
intent of finding errors.
Use carefully planned test strategies and realistic
data.
Testing cannot show absence of faults; it can
show only that software faults are present.
Demonstrates that database and application
programs appear to be working according to
requirements.

50
Testing
Should also test usability of system.
Evaluation conducted against a usability
specification.
Examples of criteria include:
Learnability;
Performance;
Robustness;
Recoverability;
Adaptability.
Testing

51
Operational Maintenance
Process of monitoring and maintaining
database system following installation.
Monitoring performance of system.
if performance falls, may require tuning or
reorganization of the database.
Maintaining and upgrading database
application (when required).
Incorporating new requirements into database
application.

52
CASE Tools
Support provided by CASE tools include:
- data dictionary to store information about
database system’s 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.

53
CASE Tools and Database System
Development Lifecycle

54
Data Administration and Database Administration
The Data Administrator (DA) and Database Administrator
(DBA) are responsible for managing and controlling the
corporate data and corporate database, respectively.
DA is more concerned with early stages of database system
development lifecycle and DBA is more concerned with
later stages.
Management of data resource including:
database planning,
development and maintenance of standards, policies and
procedures, and conceptual and logical database design.

Approaches to Database
Development
Development Process

Two Approaches to Database
Development
56
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

Systems Development Life Cycle
57
Planning
Analysis
Physical Design
Implementation
Maintenance
Logical Design

(cont.)
58
Planning
Analysis
Physical Design
Implementation
Maintenance
Logical Design
Planning Purpose–preliminary understanding
Deliverable–request for study
Database activity–
enterprise modeling and
early conceptual data
modeling

(cont.)
59
Planning
Analysis
Physical Design
Implementation
Maintenance
Logical Design
Analysis
Purpose–thorough requirements analysis
and structuring
Deliverable–functional system specifications
Database activity–thorough
and integrated conceptual
data modeling

(cont.)
60
Planning
Analysis
Physical Design
Implementation
Maintenance
Logical Design
Logical Design
Purpose–information requirements elicitation
and structure
Deliverable–detailed design specifications
logical database design
(transactions, forms,
displays, views, data
integrity and security)

61
Planning
Analysis
Physical Design
Implementation
Maintenance
Logical Design
Physical Design
Purpose–develop technology and
organizational specifications
Deliverable–program/data
structures, technology purchases,
organization redesigns
physical database design (define
database to DBMS, physical
data organization, database
processing programs)

62
Planning
Analysis
Physical Design
Implementation
Maintenance
Logical Design
Implementation
Purpose–programming, testing,
training, installation, documenting
Deliverable–operational programs,
documentation, training materials
database implementation,
including coded programs,
documentation,
installation and conversion

63
Planning
Analysis
Physical Design
Implementation
Maintenance
Logical Design
Maintenance
Purpose–monitor, repair, enhance
Deliverable–periodic audits
database maintenance,
performance analysis
and tuning, error
corrections

Prototyping Database Methodology

65

66

67

68

Architecture for Database
Development
Development Process

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)
Enterprise Data Modeling

Determine user requirements
Determine business rules
Build conceptual data model
outcome is an entity-relationship
diagram or similar
communication
tool
population of repository
Conceptual Database Modeling

Logical Database Design
Select logical database model
commit to a database
alternative
Map Entity-Relationship
Diagrams
Normalize data structures
Specify business rules

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

Database implementation
Code and test database processing
programs
Complete documentation
Install database and convert data

Database Maintenance
Analyze database and
applications to ensure
evolving information
requirements are being met
Tune database for improved
performance
Fix errors
Provide data recovery when
needed

Documentation
most formal development methodologies
are documentation based
helps managers monitor progress and
quality of project
facilitates communication between team
members
includes models
various stages are not complete until
documentation is accepted

Managing the People Involved in
Database Development
Development Process

Managing Projects:
People Involved
79
A project is a planned undertaking of related
activities to reach an objective that has a
beginning and an end.
A project begins with the first steps of the Project
Initiation and Planning phase and ends with the
last steps of the Implementation phase.
A senior systems or database analyst will be
assigned to be project leader.
This person is responsible for creating detailed
project plans as well as staffing and supervising
the project team.

Managing Projects:
People Involved
80
A project is initiated and planned in the:
 Planning phase;
executed during Analysis, Logical Design,
Physical Design, and Implementation phases;
and closed down at the end of implementation.
During initiation, the project team is formed.
A systems or database development team can
include one or more of the following:
(cont. next slide)

Managing Projects:
People Involved
81
Business analysts
Systems analysts
Database analysts and data modelers
Users
Programmers
Database architects
Data administrators
Project managers
Other technical experts

Week 7 Database Development Process

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