UNIT 1 dbdm ad3391 unit lecture notes ppt

UNIT I: CONCEPTUAL DATA
MODELING
INTRODUCTION
Data:Raw fact i.e unprocessed data.
Eg: Suresh,25,Chennai Information:
Processed data.
Eg: The age of suresh is 25

Database:
 A Database is a collection of related data
organized in a way that data can be easily
accessed, managed and updated. Any piece of
information can be a data, for example name of
your school. Database is actualy a place where
related piece of information is stored and
various operations can be performed on it.

Database Management System (DBMS)
 The software which is used to manage database
is called Database Management System (DBMS).
For Example, MySQL, Oracle etc. are popular
commercial DBMS used in different applications.

DBMS allows users the following tasks:
 Data Definition:
 It helps in creation, modification and removal of definitions
that define the organization of data in database.
 Data Updation:
 It helps in insertion, modification and deletion of the actual
data in the database.
 Data Retrieval:
 It helps in retrieval of data from the database which can be
used by applications for various purposes.
 User Administration:
 It helps in registering and monitoring users, enforcing data
security, monitoring performance, maintaining data integrity,
dealing with concurrency control and recovering information
corrupted by unexpected failure.

Database Applications
 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

DBMS Architecture
 The DBMS design depends upon its architecture.
The basic client/server architecture is used to deal
with a large number of PCs, web servers, database
servers and other components that are connected
with networks.
 The client/server architecture consists of many PCs
and a workstation which are connected via the
network.
 DBMS architecture depends upon how users are
connected to the database to get their request done

Types of DBMS Architecture
Database architecture can be seen as a single tier or multi-tier. But
logically, database architecture is of two types like: 2-tier architecture
and 3-tier architecture.

1-Tier Architecture
 In this architecture, the database is directly available to the
user. It means the user can directly sit on the DBMS and uses it.
 Any changes done here will directly be done on the database
itself. It doesn't provide a handy tool for end users.
 The 1-Tier architecture is used for development of the local
application, where programmers can directly communicate
with the database for the quick response.
 Tier Architecture in DBMS is the simplest architecture of
Database in which the client, server, and Database all reside on
the same machine.
 A simple one tier architecture example would be anytime you
install a Database in your system and access it to practice SQL
queries. But such architecture is rarely used in production

2-Tier Architecture
 The 2-Tier architecture is same as basic client-server. In the two-
tier architecture, applications on the client end can directly
communicate with the database at the server side. For this
interaction, API's like: ODBC, JDBC are used.
 The user interfaces and application programs are run on the
client-side.
 The server side is responsible to provide the functionalities like:
query processing and transaction management.
 To communicate with the DBMS, client-side application
establishes a connection with the server side.
 A 2 Tier Architecture in DBMS is a Database architecture where
the presentation layer runs on a client (PC, Mobile, Tablet, etc.),
and data is stored on a server called the second tier.
 Two tier architecture provides added security to the DBMS as it is
not exposed to the enduser directly. It also provides direct and
faster communication.

2-Tier Architecture
 In the above 2 Tier client-server architecture of
database management system, we can see that
one server is connected with clients 1, 2, and 3.

3-Tier Architecture
 The 3-Tier architecture contains another layer between
the client and server. In this architecture, client can't
directly communicate with the server.
 The application on the client-end interacts with an
application server which further communicates with the
database system.
 End user has no idea about the existence of the database
beyond the application server. The database also has no
idea about any other user beyond the application.
 The 3-Tier architecture is used in case of large web
application.

 3-Tier database Architecture design is an extension
of the 2-tier client-server architecture.
 A 3-tier architecture has the following layers:
 Presentation layer (your PC, Tablet, Mobile, etc.)
Application layer (server)
 Database Server
 The Application layer resides between the user and
the DBMS, which is responsible for communicating
the user’s request to the DBMS system and send the
response from the DBMS to the user. The application
layer(business logic layer) also processes functional
logic, constraint, and rules before passing data to
the user or down to the DBMS.

The goal of Three Tier client-server
architecture is:
 To separate the user applications and physical
database
 To support DBMS characteristics
 Program-data independence
 Supporting multiple views of the datA

Three schema Architecture
 The three schema architecture is also called
ANSI/SPARC architecture or three-level architecture.
 This framework is used to describe the structure of
a specific database system.
 The three schema architecture is also used to
separate the user applications and physical
database.
 The three schema architecture contains three-
levels. It breaks the database down into three
different categories.

DATABASE ENVIRONMENT
One of the primary aims of a database is to
supply users with an abstract view of data,
hiding a certain element of how data is stored
and manipulated. Therefore, the starting point
for the design of a database should be an
abstract and general description of the
information needs of the organization that is to
be represented in the database. And hence you
will require an environment to store data and
make it work as a database

VIEWS OF DATA/DATA ABSTRACTION
A major purpose of a database system is to provide
users with an abstract view of data. Ie., the
system hides certain details of how the data are
stored and maintained.
Three Schema Architecture:
Separates the user applications and physical
database.

Schemas can be defined in three levels:
 (i) Internal Level:
 It has an internal schema which describes
physical storage structure of the database. How
the data are actually stored uses physical model
 Describes the complete details of data storage
and access paths for the database.e.g., customer

(ii) Conceptual Level
It has an conceptual schema which describes the structure of
whole database
What data are stored and what relationships exist among
data.
Uses high level or implementational data model.
Hides the details of physical storage structures and describes
datatypes, relationships, operations and constraints.
Eg: typecustomer = record customer_id : string;
customer_name : string;
customer_street : string;
customer_city : string;
end

(iii) External or View Level
 includes a number of external schemas or
views.
 Each external schema describes the part of the
database and hides the rest.
 Uses high level or implementation data model.
such as an employee’s salary

UNIT 1 dbdm ad3391 unit lecture notes ppt

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UNIT 1 dbdm ad3391 unit lecture notes ppt