Introduction to Database System-WEEK2.pptx

INTRODUCTION TO DATABASE SYSTEM

DATA
• Data is a raw, unanalyzed, unorganized, unrelated, and an uninterrupted entity
• It is derived from the Latin word “Datum” which means ‘something given’.
• There are multiple forms of data such as numbers, letters, set of characters,
images and graphics
• Examples: weights, prices, costs, numbers of items sold,
employee names, etc.

EXAMPLE
•29061996
•Is it
• A birthday
• A bank account number
• A telephone number

INFORMATION
Information is a set of data that is processed in a
meaningful way according to the given requirement.
Example: The student’s average grade for each class,
Survey Reports and Results, Census Report, etc.

EXAMPLE 2
• RED
• What information we attached to the the red color is information
• For example:
• On traffic light it means stop
• In certain places the red color may mean danger zone

IDENTIFY IF ITS DATA OR INFORMATION
•An email
OPTION A= DATA
OPTION B = INFORMATION

•BANK STATEMENT
OPTION A= DATA

•YES, NO, YES, NO, NO, YES
OPTION A= DATA

DATA DICTIONARY
• The data dictionary contains information of the data stored in the database and is
consulted
by the DBMS before any manipulation operation on the database. It is an integral part of
the database management systems and store meta data

METADATA
.
describes the database structure, sizes of data types constraints, applications,
autorization etc., that are used as an integral tool for information resource management

DATABASE
• A database is a collection of information that is organized so that it can be easily accessed,
managed and updated. Data is organized into rows, columns and tables, and it is indexed to
make it easier to find relevant information. Data gets updated, expanded and deleted as new
information is added
• Fields - It is the smallest unit of the data that has meaning to its users and is also called data
item or data element. Name, Address and Telephone number are examples of fields
•
• Records - a collection of logically related fields and each field is possessing a fixed number
of bytes and is of fixed data type.
•
• Files - A file is a collection of related records
•

Introduction to Database System-WEEK2.pptx

COMPONENTS OF A DATABASE
1. Data item - It is defined as a distinct
piece of information
2. Relationships - It represents a
correspondence between various data
elements.
3. Constraints - These are the predicates
that define correct database states.
4. Schema - It describes the organization of
data and relationships within the database.

DATABASE SYSTEM APPLICATION
1. Banking: all transactions
2. Airlines: reservations, schedules
3. Universities: registration, grades
4. Sales: customers, products, purchases
5. Online retailers: order tracking, customized recommendations
6. Manufacturing: production, inventory, orders, supply chain
7. Human resources: employee records, salaries, tax deductions

TRADITIONAL FILE SYSTEM VERSUS DATABASE
MANAGEMENT SYSTEMS

FILE BASE SYSTEM
• each file is independent of other file, and data in different files
can be integrated only by writing individual program for each
application.

DATABASE MANAGEMENT SYSTEM
• It is a software package designed to interact with end- users, other applications, store and
manage databases. A general-purpose DBMS allows the definition, creation, querying,
update, and administration of databases.

Advantages of Database Systems Disadvantages of Database Systems
1. Controlled redundancy
2. Data consistency
3. Program data independence
4. Sharing of data
5. Enforcement of standards
6. Improved data integrity
7. Improved security
8. Data access is efficient
9. Improved backup and recovery
facility
10.Minimal program maintenance
1. Complexity increases
2. Requirement of more disk space
3. Additional cost of hardware
4. Cost of conversion
5. Need of additional and specialized
manpower
6. Need for backup and recovery
7. Organizational conflict
8. More installation and management
cost

COMPONENTS OF DBMS
• Data Definition Language (DDL)
• It allows the users to define the database, specify the
data types, data structures and the constraints on the data to
be stored in the database
• Data Manipulation Language (DML) and Query
Language
DML allows users to insert, update, delete and retrieve data
from the database
• Software for Controlled Access of Database
This software provides the facility of controlled access of the
database by the users,concurrency control to allow shared
access of the database and a recovery control system to
restore the database in case of ardware or software failure.

DATABASE SYSTEM ENVIRONMENT
• Users- People who interact with the database:
Application Programmers.
End Users.
Data - Data Administrators
• Software- Lies between the stored data and the users:
- DBMS.
- Application Software.
- User Interface.
• Hardware- Physical device on which database resides.
e.g.: of database Computers, Disk Drives, Printers, Cables etc.

DBMS USERS
• End Users - use the database system through a menu-oriented application program, where
the type and range of response is always displayed on the screen
• Online Users - These type of users communicate with the database directly through an online
terminal or indirectly through an application program and user interface.
• Application Programmers - These are the professional programmers or software developers
who develop the application programs or user interfaces for the end user/naive and online
users.
• Database Administrator - a person who have complete control over database of any
enterprise. DBA is responsible for overall performance of database.

SCHEMAS, SUBSCHEMA AND INSTANCES

SCHEMA
• A schema is plan of the database that give the names of the entities and attributes and the
relationship among them.
• THREE TYPES OF SCHEMA
1.logical schema is concerned with exploiting the data structures offered by the
DBMS so that the schema becomes understandable to the computer. It is important
as programs use it to construct applications.
2.physical schema is concerned with the manner in which the conceptual database get
represented in the computer as a stored database.
3.View schema: Design of database at view level is called view schema. This generally
describes end user interaction with database systems

SCHEMA
• Subschema
A subschema is a subset of the schema having the
same properties that a schema has. It
identifies a subset of areas, sets, records, and data
names defined in the database schema
available to user sessions. The subschema allows
the user to view only that part of the
database that is of interest to him. The subschema
defines the portion of the database as
seen by the application programs and the application
programs can have different view of data stored in
the database.
• Instances - The data in the database or a database
state.

THREE LEVEL ARCHITECTURE OF DATABASE SYSTEMS (DBMS)
BY ANSI/SPARC
1. external level - The users’ view of the
database. This level describes that part
of the
database that is relevant to each user.
2. conceptual level - The community view
of the database. This level describes what
data
is stored in the database and the
relationships among the data.
3. internal level The physical
representation of the database on the
computer. This level describes how the
data is stored in the database.

DATA MODELS
A DATA MODEL IS A COLLECTION OF CONCEPTS THAT CAN BE USED TO
DESCRIBE THE STRUCTURE OF THE DATABASE INCLUDING DATA TYPES,
RELATIONSHIPS AND THE CONSTRAINTS THAT APPLY ON THE DATA

THREE CATEGORIES OF DATA MODEL

RECORD BASE DATA MODEL
represent data by using the record structures

HIERARCHICAL DATA MODEL
Hierarchical Data Model - organizes records in a tree structure i.e., hierarchy of parent and child records
relationships.

NETWORK MODEL
Network Data Model - The ability of this model to handle many to many (N : N)
relations between its records is the main distinguishing feature from the hierarchical model. Thus, this
model permits a child record to have more than one parent.

RELATIONAL DATA MODEL
Relational Data Model - represented in the form of tables which is used interchangeably with the word
Relation. Each table consists of rows also knowns as tuples

ENTITY RELATIONSHIP MODEL (ER-MODEL)
• allows the representation of the various constraints as well as their relationships.
• The properties of these entities are their attributes in the ER diagram and their connections
are shown in the form of relationships.

OBJECT BASED DATA MODELS
These models are used in describing the data at the logical and user view levels.
These models allow the users to implicitly specify the constraints in the data

OBJECT ORIENTED MODEL
• Object oriented data model is also based on using real life scenarios. In this model, the scenarios
are represented as objects. The objects with similar functionalities are grouped together and linked
to different other objects.
• used for multimedia applications as well as data with complex relationships.

SEMANTIC DATA MODEL
• used to express greater interdependencies among
entities of interest. This class of data models are
influenced by the work done by artificial intelligence
researchers.

FUNCTIONAL DATA MODEL
The functional data model describes those aspects of a system concerned with transformation of
values-functions, mappings, constraints and functional dependencies

PHYSICAL DATA MODELS
These models provide the concepts that describes the details of how the data is stored
in the computer along with their record structures, access paths and ordering. Only
specialized or professional users can use these models

TWO TYPES OF PHYSICAL DATA MODEL
a. Unifying Model.
a. Frame Memory Model

CATEGORIES OF DATABASE SYSTEMS
• According to the Number of Users
• According to the Type of Use
• According to Database Site Locations

ACCORDING TO THE NUMBER OF
USERS
a. Single-user database systems - In a single user database system, the database reside
on a PC–on the hard disk. All the applications run on the same PC and directly access the
database.
b. Multiuser database systems - many PC’s are connected through a Local Area Network (LAN)
and a file server stores a copy of the database files.

ACCORDING TO THE TYPE OF USE
a. Production or Transactional Database Systems – used for management of supply chain
and for tracking production of items in factories, inventories of items in warehouses/stores
and orders for items.
b. Decision Support Database Systems - an interactive, computer-based systems that aid
users in judgement and choice activities
c. Data Warehouses - designed specifically to meet the transaction processing systems. It
can be loosely defined as any centralized data repository which can be queried for business
benefit.

ACCORDING TO DATABASE SITE LOCATIONS
a. Centralized database systems - consists of a single processor together with its associated data storage
devices and other peripherals. Database files resides on a personal computer (small enterprise) or on a
mainframe computer
b. Parallel database systems - used in the applications that have to query
extremely large databases or have to process an extremely large number of transactions per second
c. Distributed database systems - the data is spread across a variety of different databases
•
d. Client/Server database systems - In client/server technology, there is a server which acts as a whole data
base management system and some clients or personal computers which are connected with server through a
network interface.

Introduction to Database System-WEEK2.pptx

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