Wolaita Sodo University

School of Informatics
Department of Information Technology
Course Instructor : Tadele Sh.
Assisted by:-_____
Email Address: 4tadegu@gmail.com
Program:-Regular
A.Year:- 2024/2nd year
Section:- 1
Fundamentals of database Systems
(ITec2071)
 Chapter One:- Introduction
Outline
 Introduction to database system
 File based verses Database approach
 Components of DBMS
 Functions of DBMS
 Database Development Lifecycle
 Characteristics of the Database Approach
 Roles in database design environment
 The ANSI-SPARC Architecture
 Database Languages
 Data models
 Introduction

A database (DB) is a collection of related data, we mean known

facts that can be recorded and that have implicit meaning.
For example:- consider the names, tele-phone numbers, and
addresses of the people you know. You may have recorded this data
in an indexed address book or you may have stored it on a hard
drive, using a personal computer and software such as Microsoft
Access or Excel.
This collection of related data with an implicit meaning is a
database.
 Cont’d…
A database has the following implicit properties:
 A database represents some aspect of the real world, sometimes
called the mini world or the universe of discourse (UoD).
 A database is a logically coherent collection of data with some
inherent meaning.
A random assortment(mixture) of data cannot correctly be
referred to as a database.
 A database is designed, built, and populated with data for a
specific purpose. It has an intended group of users and some
preconceived applications in which these users are interested.
 Cont’d…
A database management system (DBMS) is a collection of programs
that enables users to create and maintain a database.
The DBMS is a general-purpose software system that facilitates the
processes of defining, constructing, manipulating, and sharing
databases among various users and applications.
Defining a database involves specifying the data types, structures,
and constraints of the data to be stored in the database.
 Cont’d…
The database definition or descriptive information is also stored by
the DBMS in the form of a database catalog or dictionary; is called
metadata.
Constructing the database is the process of storing the data on some
storage medium that is controlled by the DBMS.
A typical large database may have a life cycle of many years, so the
DBMS must be able to maintain the database system by allowing
the system to evolve as requirements change over time.

To complete our initial definitions, we will call the database and

DBMS software together a database system.

 File-Based Approach vs Database Approach

File-based System
 File-based systems were an early attempt to computerize the
manual filing system.
 File-based system is a collection of application programs that
perform services for the end-users. Each program defines and
manages its data. Each user defines and creates with a specific
software the files s/he needs for a specific application e.g.. Spread
sheet
However, five types of problem are occurred in using the file-based
approach:
 Problems of using file based approach
 Separation and isolation of data

When data is isolated in separate files, it is more difficult for us to

access data that should be available.
 Duplication of data

i. Duplication is wasteful
ii. Duplication can lead to loss of data integrity
 Data dependence

The physical structure and storage of the data files and records
are defined in the application program code.
 Cont’d…
 Incompatible file formats

The structures of the file are dependent on the application

programming language. However file structure provided in one
programming language such as direct file, indexed-sequential file
which is available in COBOL programming, may be different from
the structure generated by other programming language such as C.
 Fixed queries / proliferation of application programs

File-based systems are very dependent upon the application

programmer. Any required queries or reports have to be written by
the application programmer.
 Database Approach:

In order to overcome the limitations of the file-based approach, the concept of

database and the Database Management System (DMS) was emerged in 60s.
Advantages of data base approach
 Control of data redundancy

The database approach attempts to eliminate the redundancy by integrating the file.
 Data consistency

By eliminating or controlling redundancy, the database approach reduces the risk of

inconsistencies occurring.
 More information from the same amount of data

With the integration of the operated data in the database approach, it may be
possible to derive additional information for the same data.
 Cont’d…
 Sharing of data
 Improved data integrity
 Improved security
 Enforcement of standards

The integration of the database enforces the necessary

standards including data formats, naming conventions,
documentation standards, update procedures and access
rules.
 Economy of scale
Cont’d…
 Balance of conflicting requirements
 Improved data accessibility and responsiveness

By having an integration in the database approach, data accessing can be

crossed departmental boundaries.
 Increased productivity
 Improved maintenance

Database approach provides a data independence. As a change of data structure

in the database will be affect the application program, it simplifies database
application maintenance.
 Increased concurrency
 Improved backing and recovery services
 Disadvantage of database approcah

 Complexity
 Size
 Cost of DBMS
 Cost of conversion
 Performance
 Higher impact of a failure
 Characteristics of database approach
The main characteristics of the database approach versus the
file-processing approach are the following:
 Self-describing nature of a database system
 Insulation between programs and data, and data abstraction
 Support of multiple views of the data
 Sharing of data and multi-user transaction processing
 Self-Describing Nature of a Database System
A fundamental characteristic of the database approach is that the

database system contains not only the database itself but also a

complete definition or description of the database structure and

constraints.

This definition is stored in the DBMS catalog, which contains

information such as the structure of each file, the type and storage

format of each data item, and various constraints on the data.

The information stored in the catalog is called meta-data, and it

describes the structure of the primary database.

 Insulation between Programs and Data,
and Data Abstraction

In traditional file processing, the structure of data files is embedded

in the application programs, so any changes to the structure of a file
may require changing all programs that access that file.
By contrast, DBMS access programs do not require such changes in
most cases.
The structure of data files is stored in the DBMS catalog separately
from the access programs.
We call this property program-data independence.
 Support of Multiple Views of the Data

A database typically has many users, each of whom may require a

different perspective or view of the database.
A view may be a subset of the database or it may contain virtual
data that is derived from the database files but is not explicitly
stored.
Sharing of data and multiuser transaction processing

A multiuser DBMS, as its name implies, must allow multiple users

to access the data-base at the same time.
This is essential if data for multiple applications is to be integrated
and maintained in a single database.
The concept of a transaction has become central to many database
applications.
A transaction is an executing program or process that includes one
or more database accesses, such as reading or updating of database
records.
 Roles in database design environment

1.Database administrator (DBA)

The DBA is responsible for authorizing access to the database, coordinating

and monitoring its use, and acquiring software and hardware resources as
needed.

The DBA is accountable for problems such as security breaches and poor
system response time.

2.Database designers(DBD) :

DBDs are responsible for identifying the data to be stored in the database and
for choosing appropriate structures to represent and store this data.

It is the responsibility of database designers to communicate with all

prospective database users in order to understand their requirements and to
create a design that meets these requirements.
 Cont’d…
3.End users :
are the people whose jobs require access to the database for
querying,updating, and generating reports; the database primarily
exists for their use.
There are several categories of end users:
A. Casual end users: occasionally access the database, but they
may need different information each time.
 Cont’d…
B. Naive or parametric end users: make up a sizable portion of
database end users. Their main job function revolves around
constantly querying and updating the database, using standard types
of queries and updates.
C. Sophisticated end users: include engineers, scientists, business
analysts, and others who thoroughly familiarize themselves with the
facilities of the DBMS in order to implement their own applications
to meet their complex requirements.
D. Standalone users: maintain personal databases by using ready-
made program packages that provide easy-to-use menu-based or
graphics-based interfaces.
 4. System Analysts and Application Programmers
(Software Engineers)
System analysts determine the requirements of end users,
especially naive and parametric end users, and develop
specifications for standard canned transactions that meet these
requirements.
Application programmers implement these specifications as
programs; then they test, debug, document, and maintain these
recorded transactions.
 The ANSI-SPARC Architecture

The ANSI-SPARC three layer

database architecture was proposed
in 1975, and is still used in modern
RDBMS. The three proposed layers
were a physical schema: which
defined how the data is actually
stored (inode information), a
conceptual schema: which
represented how information was
related and indexed, and an external
schema: which represented how
information was presented.
 Internal Schema
The internal schema, represents the "machine view" of the data in the
data base, and describes how data is stored and accessed in the data
base.
The logical and the physical data access paths are defined in the
internal schema of an ANSI/SPARC architecture.
Logical access paths refer to aspects like partitioning and
materialization, while the physical access paths define low level
access structures like indexes.
The internal schema describes the storage structures of the database.
 Conceptual schema
The "conceptual level" of a data base system is an undefined but
often used expression.
The conceptual schema is a distinguished property of an
ANSI/SPARC type data base management system.
Independent of the data base management systems used to
implement an information system, the designers will need and use an
implicit or explicit conceptual data structure.
The conceptual level design is concerned with specification,
determination, formal description and analysis of information to be
contained in a (database) system.
 External Schema
The external schema in the ANSI/SPARC architecture comprises
user-defined data views, which can be seen as virtual tables storing
the results of specific queries.
A view can comprise attributes of multiple tables as well as pre-
defined aggregations or calculation results.
External schemas describe different views of a database for particular
users or groups of users, providing features such as logic
independence, authorization, and integration of heterogeneous
databases
Cont’d..
.
 Database Languages
SQL is a database language designed for the retrieval and
management of data in a relational database.
SQL is the standard language for DBMS.
All the RDBMS systems like MySQL, MS Access, Oracle, Sybase,
Postgres, and SQL Server use SQL as their standard database
language. SQL programming language uses various commands for
different operations.
Here are five types of widely used SQL queries.
A. Data Definition Language (DDL) D. Data Control Language(DCL)

 B. Data Manipulation Language (DML) E. Data Query Language (DQL)

 C. Transaction Control Language(TCL)


Database Languages/Types of SQL
 Data models
 One fundamental characteristic of the database approach is that it
provides some level of data abstraction (refers to the
suppression of details of data organization and storage, and the
highlighting of the essential features for an improved
understanding of data.).
 A data model :- a collection of concepts that can be used to
describe the structure of a database (provides the necessary means
to achieve this abstraction.). By structure of a database we mean
the data types, relationships, and constraints that apply to the
data. Most data models also include a set of basic operations for
specifying retrievals and updates on the database.
 Cont’d...
Reading Assignment
Categories of Data Models:-

 High-level or conceptual data model,

 Low-level or physical data model,
 Representational ( implementation) data model,
 Entity-Relationship model,
 Relational data model,
 Network and hierarchical model
 Record-based data model
 Object data model
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Monday, December 2, 202 By Tadele sh (SavedByGrace)

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