Database Management System Lecture SlideCh-1.ppt

Chapter 1: Introduction to Database
Systems
Fundamentals of Database Systems (CoSc2041)
Prepared by: Gebriye Embafresu
Computer Science Department
gebriye14@gmail.com
Oct 01, 2024

© 2024, Gebriye E. Dept. Computer Science HCIA Security, HCIA R&S and HCIP R&S Certified
Outline
• Define what is
– Data,
– Database
– Database Management System,
– and Database system
• Database System Applications
• Purpose of Database Systems
• Database system and file based approach
• Database users and Administrators
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What is Data?
• The term data refers to known raw facts about
things like people, places, events and concepts.
• The word raw indicates that the facts have not yet
been processed to reveal their meaning.
• Data is any fact that can be recorded (or) stored into
a computer hard disk.
• there are various forms of data, like video, audio
image, graphics, text document,
• Data is raw , unprocessed fact.
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Information and Knowledge
• Information is the processed data presented in a form suitable for human
interpretation.
• Information is the result of processing raw data to reveal its meaning.
• Knowledge:
– The body of information and facts about a specific subject.
– Knowledge implies familiarity, awareness, and understanding of
information as it applies to an environment.
– A key characteristic is that new knowledge can be derived from old
knowledge.
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Database
• A database is an organized collection of interrelated data, generally stored
and accessed electronically from a computer system.
• It contains information relevant to an enterprise.
E.g.: Online Banking System, University website,
• Management of data involves both defining structures for storage of
information and providing mechanisms for the manipulation of information.
• The database is an important assets for many organizations.
• Database touch all aspects of our lives.
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Database (Cont.)
• The database is an integrated collection of facts about an organization.
• Organization can be a University or a department in a University , Insurance companies,
Manufacturing companies, Banks, Airlines, Telecommunications, Governmental and Non-
governmental Organizations, Research institutions ,etc.
• The database is used as a central data source for other applications
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Database Management System
• Database Management System is a program or software which is used to define,
construct, manipulate, share and retrieve the data in the database.
• A database management system (DBMS) is a collection of usually complex
pieces of software that allows a user to define, create, manipulate and protect and
manage access to a database.
• The primary goal of a DBMS is to provide a way to store and retrieve database
information that is both convenient and efficient.
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Database Management System
Functionalities:
•Define: Specifying the data type, structure, and constraints for the data to be stored.
•Construct: Process of storing data on some storage medium.
•Manipulate: Querying the database to retrieve specific data, updating database and generating
reports.
•Share: Allows multiple users and programs to access the database concurrently.
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Database Systems
• A database system is a collection of interrelated data and a
set of programs that allow users to access and modify these
data.
• Database systems are used to manage collections of data
that are:
– Highly valuable,
– Relatively large, and
– Accessed by multiple users and applications, often at the same time.
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Database Systems (Cont’d…)
• A modern database system is a complex software system whose
task is to manage a large, complex collection of data.
• The database system must ensure the safety of the information
stored, despite system crashes or attempts at unauthorized access.
• Database systems are ubiquitous today, and most people interact,
either directly or indirectly, with databases many times every day.
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Database Applications Examples
• Manufacturing: management of production, inventory, orders, supply
chain.
• Banking and finance
– customer information, accounts, loans, banking transactions, and
bank staff details.
– Credit card transactions
– Finance: sales and purchases of financial instruments (e.g.,
stocks and bonds; storing real-time market data
• Universities: registration of students, Store grades, transcripts,
academic progress, manage course offerings, schedules, and
prerequisites.
Here are some of the applications of database system
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Database Applications Examples (Cont.)
• Airlines: reservations and booking of ticket, manage flight
schedules, staff and passenger information, and real-time flight
update
• Telecommunication: keeping records of calls made, texts, and
data usage, generating monthly bills, maintaining balances on
prepaid calling cards
• Web-based services
– Online retailers: order tracking, customized recommendations
– Online advertisements
• Navigation systems: For maintaining the locations of varies places
of interest along with the exact routes of roads, train systems,
buses, etc.
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Purpose of Database Systems
• Data redundancy and inconsistency
– data is stored in multiple file formats resulting induplication of
information in different files
• Difficulty in accessing data
– Need to write a new program to carry out each new task
• Data isolation
– Multiple files and formats
• Integrity problems
– Integrity constraints (e.g., account balance > 0) become “buried” in
program code rather than being stated explicitly
– Hard to add new constraints or change existing ones
In the early days, database applications were built directly on top of file systems, which
leads to:
13
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Purpose of Database Systems (Cont.)
• Atomicity of updates
– Failures may leave database in an inconsistent state with partial updates carried
out
– Example: Transfer of funds from one account to another should either complete
or not happen at all
• Concurrent access by multiple users
– Concurrent access needed for performance
– Uncontrolled concurrent accesses can lead to inconsistencies
• Ex: Two people reading a balance (say 100) and updating it by withdrawing
money (say 50 each) at the same time
• Security problems
– Hard to provide user access to some, but not all, data
Database systems offer solutions to all the above problems
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Example University Database
• Mini-world for a University Database example: Part of a
UNIVERSITY environment.
• Some mini-world entities:
– STUDENTs
– PRE-REQUISITE COURSEs
– COURSEs
– DEPARTMENTs
– INSTRUCTORs
Note: The above could be expressed in the ENTITY-
RELATIONSHIP data model.
15

University Database Example
• Data consists of information about:
– Students
– Instructors
– Classes
• Application program examples:
– Add new students, instructors, and courses
– Register students for courses, and generate class
rosters
– Assign grades to students, compute grade point
averages (GPA) and generate transcripts
16

Example University Database(Continued…)
• Some mini-world relationships:
– STUDENTs take COURSEs
– COURSEs have PRE-REQUISITE COURSEs
– INSTRUCTORs teach COURSEs
– COURSEs are offered by DEPARTMENTs
– STUDENTs major in DEPARTMENTs
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Example Relational Database Snapshot
18

© 2024, Gebriye E. Dept. Computer Science HCIA Security, HCIA R&S and HCIP R&S Certified 19
Evolution of Database Systems
• Two approaches to convert data to information:
– File-based
• Developed starting from 1960’s
• Stores, manipulates, retrieves data from large flat files
– Database (relational systems)
• Developed by E. F. Codd of IBM the early 1980's
• Widely used today
Evolution of
Database
Systems

File-Based Approach
• A file is a collection of related information
• A system of files and collection of application programs
manipulating them is a file-based system
University
File-Based System

Limitations of File-Based Approach
• Much efforts for ad hoc query answering:
– What is the average grade for Mr.Negacy’s student?
– List the activities for all students enrolled in CoSc2041.
– Which personnel are students as well as staff?
• Other limitations:
– Duplication of data
– Data dependency
– Slow development, high maintenance and fixed queries

Database Users and Administrators
• A primary goal of a database system is to retrieve
information from and store new information in the
database.
• People who work with a database can be categorized as
– database users or
• Naïve users
• Application programmers
• Sophisticated users
– database administrators.
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database users
• Naive users are unsophisticated users who
interact with the system by using predefined user
interfaces, such as web or mobile applications.
• The typical user interface for naive users is a forms
interface, where the user can fill in appropriate
fields of the form.
• Naive users may also view read reports generated
from the database.
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database users
• Application programmers are computer professionals who
write application programs. Application programmers can
choose from many tools to develop user interfaces.
• Sophisticated users interact with the system without writing
programs. Instead, they form their requests either using a
database query language or by using tools such as data
analysis software.
• Analysts who submit queries to explore data in the
database fall in this category.
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Database Administrator
 Schema definition
 Storage structure and access-method definition
 Schema and physical-organization modification
 Granting of authorization for data access
 Routine maintenance
 Periodically backing up the database
 Ensuring that enough free disk space is available for normal
operations, and upgrading disk space as required
 Monitoring jobs running on the database
A person who has central control over the system is called a database administrator
(DBA). Responsibilities of a DBA include:
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Responsibilities of DBA
• Schema definition.
The DBA creates the original database schema by executing
a set of data definition statements in the DDL.
•Storage structure and access-method definition.
The DBA may specify some parameters pertaining to the
physical organization of the data and the indices to be created.
• Schema and physical-organization modification.
The DBA carries out changes to the schema and physical
organization to reflect the changing needs of the organization,
or to alter the physical organization to improve performance.
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Responsibilities of DBA (Cont’d.)
• Granting of authorization for data access.
By granting different types of authorization, the database administrator
can regulate which parts of the database various users can access.
The authorization information is kept in a special system structure that
the database system consults whenever a user tries to access the data
in the system.
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Responsibilities of DBA (Cont’d.)
• Routine maintenance.
Examples of the database administrator’s routine maintenance activities are:

Periodically backing up the database onto remote servers, to prevent loss of data in case of disasters such as
flooding.

Ensuring that enough free disk space is available for normal operations, and upgrading disk space as required.

Monitoring jobs running on the database and ensuring that performance is not degraded by very expensive
tasks submitted by some users.
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Fundamentals of Database Systems
End of Chapter Two !!!
Have a nice day!!
Never Stop Learning!
1-29

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