UNIT-I (15 Hours)
Database and Database Users: Introduction, Characteristics of the Database Approach, Actors on
the Scene, Workers behind the Scene, Advantages of the using the DBMS Approach.
Database System Concepts and Architecture: Data Models, Schemas and Instances, Three
Schema Architecture and Data Independence, Database Languages and Interfaces, Centralized
and Client/Server Architecture for DBMS, Classification of Database Management Systems.
Introduction
● A database is a collection of related data.
● By data, we mean known facts that can be recorded and that have implicit meaning.
● A database represents some aspect of the real world, sometimes called the
miniworld.
● A database is a logically coherent collection of data with some inherent meaning.
● 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.
● A database has some source from which data is derived, some degree of interaction
with events in the real world, and an audience that is actively interested in its
contents.
● The end users of a database may perform business transactions.
● it must be a true reflection of the miniworld that it represents; therefore, changes
must be reflected in the database as soon as possible.
● A database can be of any size and complexity.
● A database management system (DBMS) is a computerized system 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. The database definition or descriptive
information is also stored by the DBMS in the form of a database catalog or
dictionary; it is called meta-data.
● Constructing the database is the process of storing the data on some storage medium
that is controlled by the DBMS.
, ● Manipulating a database includes functions such as querying the database to
retrieve specific data, updating the database to reflect changes in the miniworld, and
generating reports from the data.
● Sharing a database allows multiple users and programs to access the database
simultaneously. An application program accesses the database by sending queries or
requests for data to the DBMS.
● Other important functions provided by the DBMS include protecting the database
and maintaining it over a long period of time. Protection includes system protection
against hardware or software malfunction (or crashes) and security protection
against unauthorized or malicious access
● we will call the database and DBMS software together a database system.
Characteristics of the 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
Database and Database Users: Introduction, Characteristics of the Database Approach, Actors on
the Scene, Workers behind the Scene, Advantages of the using the DBMS Approach.
Database System Concepts and Architecture: Data Models, Schemas and Instances, Three
Schema Architecture and Data Independence, Database Languages and Interfaces, Centralized
and Client/Server Architecture for DBMS, Classification of Database Management Systems.
Introduction
● A database is a collection of related data.
● By data, we mean known facts that can be recorded and that have implicit meaning.
● A database represents some aspect of the real world, sometimes called the
miniworld.
● A database is a logically coherent collection of data with some inherent meaning.
● 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.
● A database has some source from which data is derived, some degree of interaction
with events in the real world, and an audience that is actively interested in its
contents.
● The end users of a database may perform business transactions.
● it must be a true reflection of the miniworld that it represents; therefore, changes
must be reflected in the database as soon as possible.
● A database can be of any size and complexity.
● A database management system (DBMS) is a computerized system 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. The database definition or descriptive
information is also stored by the DBMS in the form of a database catalog or
dictionary; it is called meta-data.
● Constructing the database is the process of storing the data on some storage medium
that is controlled by the DBMS.
, ● Manipulating a database includes functions such as querying the database to
retrieve specific data, updating the database to reflect changes in the miniworld, and
generating reports from the data.
● Sharing a database allows multiple users and programs to access the database
simultaneously. An application program accesses the database by sending queries or
requests for data to the DBMS.
● Other important functions provided by the DBMS include protecting the database
and maintaining it over a long period of time. Protection includes system protection
against hardware or software malfunction (or crashes) and security protection
against unauthorized or malicious access
● we will call the database and DBMS software together a database system.
Characteristics of the 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
