-This lecture about the Details explanation about the Database Development life Cycle. This lecture show about the Software development Cycle in term of DB. This lecture Explain the architecture of the Database. This lecture explain about the Three-Level ANSI-SPARC Architecture.

1. Institute of SouthernPunjab,
Multan
Mr. Saif ur Rehman Khan
BS (Computer Science)
MS (Data Science, and Computer Science)
Honors:
Certified Android Developer, Research Assistant
E-Mail: saifurrehman.khan@outlook.com

2. 2
Database Systems
Lecture#2
Databases Environment

3. Lecture 02 - Objectives
 System Development Life Cycle (SDLC)
 Database Development Process (DDP)
 The Three-Level ANSI-SPARC Architecture
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4. System Development Life Cycle (SDLC)
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5. Information System
 Definition:
Information systems are combinations of hardware,
software, and telecommunications networks that people
build and use to collect, create, and distribute useful data,
typically in organizational settings.
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6. System Development Life Cycle
 Definition:
A traditional process for conducting an information
systems development project is called System Development
Life Cycle (SDLC). The SDLC is a complete set of steps
that a team of information systems professionals, including
database designers and programmers, follow in an
organizations to specify, develop, maintain, and replace
information system. Organization use many variations on
the life cycle, and many identify anywhere from three to
twenty different phases. This process is depicted in
upcoming slides. Ref (Hoffer et al., 2005).
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 System Development Life Cycle (SDLC):
The traditional methodology used to develop, maintain
and replace information system.
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9. System Development Life Cycle
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10. Database Development Process (DDP)
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11. Database Development Process (DDP)
Database Application development Process includes the
Following steps:
1. Preliminary / initial Study
2. Requirement Analysis
3. Database Design
4. Physical Design
5. Implementation
6. Maintenance
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12. Problems with Data Dependency
 If data is being changed then the program must be changed and vice
versa For example if a library system has some attributes about book
like.
 Book_id
 Book_name
 Book_title
 Book_author
And after some time we add an other attribute like
book_edition. So you need to change data but on other
hand you have to change the program as well because
program is dependent on data and vice versa It means that
if you change the data in library system you will have to
change Examination and Registration systems.
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13. Preliminary Study
 First Phase of the database development process is the
Preliminary Study, which is based on the proper study of the
system.
 It means that all the parts of the systems, or the section of the
subject organization for which we intend to develop the system
must be studied.
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 We should find the relation or interaction of different section of
the organization with each other and should understand the way
information flows between different sections of the
organization.
 Moreover it should also be made clear that what processing is
performed at each stage of the system.
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15. Requirement Analysis
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 In second phase, The detailed functionality decisions made at
this of the organization. study of the system and its stage
decide the overall activity of an organization.
 Requirements of one section of the organization are fulfilled in
such a way that all the sections in the organization are
supporting each other.

16. Example
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17. Database Design
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 Third phase in the database development process is the
database design.
 This is a technical phase of the process and need handsome
skill as a Database Administrator. This is the phase where the
conceptual design of the database is created. It also known as
Conceptual Data Modeling.
 Entities are identified and given attributes, relationships are
built and different types of relationship are performed by
assigning cardinalities.

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 Cardinality (data modeling) In database design, the
cardinality or fundamental principle of one data aspect with
respect to another is a critical feature. The relationship of one
to the other must be precise and exact between each other in
order to explain how each aspect links together.

19. Physical Design
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 In fourth phase, The choice of the DBMS is made on the basis
of requirements and the environment in which the system will
operate.
 Implementing a database on a specific DBMS is very important
because it involves the major financial investment of the
organization, and can not be reverted in case a selected DBMS
in not capable of providing the desired efficiency.
 Also, Assigning meaningful Data Types,
Constraints/Limitations and De-Normalization of Data
where required by the real time scenario/system are to be
finalized and processed in this phase.

20. Implementation
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 This phase is specific to writing the application programs
needed to carry out different activities according to user
requirements.
 We must write application programs in this phase.
 We can done coding with out implemented all previous phases
correctly.

21. Maintenance
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 Maintenance means to fine tune the system and check that the
designed applications systems are fulfilling the purpose for
which they are meant.
 Also, this phase may involve designing any new application for
the enhancement of the system.
 Or an already working application may need to be updated or
modified to remove any errors or to add some functionality in
the system.

22. The Three-Level ANSI-SPARC Architecture
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23. The Three-Level ANSI-SPARC Architecture
• An early proposal for a standard terminology and general
architecture for database systems was produced in 1971 by the
Data Base Task Group (DBTG) appointed by the Conference
on Data Systems and Languages (CODASYL, 1971).
•
• The Data Base Task Group (DBTG) recognized the need for a
two-level approach with a system view called the schema and
user views called subschemas.
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 The American National Standards Institute (ANSI) Standards
Planning and Requirements Committee (SPARC),
ANSI/X3/SPARC, produced a similar terminology and
architecture in 1975 (ANSI, 1975). ANSI-SPARC recognized
the need for a three-level approach.
 Although, The ANSI-SPARC model did not become a standard,
It still provides a basis for understanding some of the
functionality of a DBMS.

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 The levels form a three-level architecture comprising an
External, Conceptual, and an Internal level.
 The way users observe the data is called the External Level
(Front End). The way the DBMS and the Operating System
perceive/stores the data (Back End) is the Internal Level.
 The Conceptual Level provides both the mapping and the
desired independence between the external and internal levels.

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 External Level:
The user’s view of the database. This level describes
that part of the database that is relevant to each user.
 Conceptual Level:
The community view of the database. This level
describes what data is stored in the database and the
relationship among the data.
 Internal/ Physical Level:
The physical representation of the database on the
computer. This level describes how the data is stored
in the database.

27. Example:
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• The overall Description/Skeleton structure of the database is called the
database schema.
• At the highest level, we have multiple external schemas (also called
subschemas) that correspond to different views of the data.
• At the conceptual level, we have the conceptual schema, which describes all
the entities, attributes, and relationships together with integrity constraints.
• At the lowest level, we have the internal schema, which is a complete
description of the internal model, containing the definitions of stored
records, the methods of representation, the data fields, and the indexes and
storage structures used. There is only one conceptual schema and one
internal schema per database.
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• The objective of the three-level architecture is to separate each
user’s view of the database from the way the database is
physically represented. There are several reasons why this
separation is desirable:-
• Each user should be able to access the same data, but have a
different customized view of the data.
• Users should not have to deal directly with physical database
storage details.
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• The internal structure of the database should be unaffected by
changes to the physical aspects of storage, such as the
changeover to a new storage device.
• The Database Administrator (DBA) should be able to change
the conceptual and database storage structures without
affecting the users’ views.

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 A major objective for the three-level architecture is to provide
data independence, which means that upper levels are
unaffected by changes to lower levels.
 . There are two kinds of data independence: -
1. Logical Data Independence.
2. Physical Data Independence

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 Logical Data Independence:
Changes to the conceptual schema, such as the addition or
removal of new entities, attributes, or relationships, should be
possible without having to change existing external schemas or
having to rewrite application programs. Clearly, the users for
whom the changes have been made need to be aware of them, but
what is important is that other users should not be.

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 Physical Data Independence:
Changes to the internal schema, such as using different file
storage structures, using different storage devices should be
possible without having to change the conceptual or external
schemas.

36. Summary of Lecture
 System Development Life Cycle (SDLC)
 Database Development Process (DDP)
 The Three-Level ANSI-SPARC Architecture
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37. END OF LECTURE 2
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