gr 1

in the context of databases, refers to all the single items that are stored in a database,
either individually or as a set.

is an organized collection of structured information, or data, typically stored
electronically in a computer system.

data is organized strictly in row and column format.

rows are called

columns are often called

Example of a Database

is a collection of interrelated data and a set of
programs to access those data.

Major areas of application of database

a database is a storage record that holds information regarding the
customers and offset transactions, including Personal Identifiable Information, deposits,
withdrawals, and transfers.

is a large-scale project which includes a database of more than
a single Airport. This airline management system contains the details about: Airplane Type,
Route, Flight, Airfare, Passengers, Employees, Transactions, Countries and Airport.

is required to manage the records of the
students. Managing student information, generating enrollment numbers, admit cards
generation are some of the modules of the University Management Software.

The retail industry has greatly benefited from the use of DBMS. Retail organizations use
DBMS to store customer information, sales data, and product details. This enables retailers
to make informed decisions, improve customer satisfaction, and increase sales.

Human resource departments use DBMS to store and manage vast amounts of employee
data, including personal information, job history, and performance data. This data is then used
to make informed decisions about employee hiring, training, and development.

The healthcare industry has greatly benefited from the use of DBMS. Electronic Health
Records (EHRs) are a prime example of how DBMS is used in healthcare. EHRs use DBMS
to store patient information, medical history, laboratory results, and other crucial data. This
has improved the accuracy and efficiency of patient care as healthcare providers can access
patient information from any location.

PURPOSE OF DATABASE SYSTEMS

Different programmers create the files and
application programs over a long period, the various files are likely to have different
structures and the programs may be written in several programming languages.
Moreover, the same information may be duplicated in several places (files).

Conventional file-processing environments do not allow
needed data to be retrieved conveniently and efficiently. More responsive dataretrieval systems are required for general use.

Data are scattered in various files, and files may be in different formats,
writing new application programs to retrieve the appropriate data is difficult.

The data values stored in the database must satisfy certain types
of consistency constraints

A computer system, like any other device, is subject to failure. In
many applications, it is crucial that, if a failure occurs, the data be restored to the
consistent state that existed prior to the failure

For the sake of the overall performance of the system
and faster response, many systems allow multiple users to update the data
simultaneously.

Enforcing a security constraint is difficult since application
programs are added to the file-processing system in an ad hoc manner.

Advantages of DBMS

In a database system, by having a centralized database and centralized control of data
by the DBA the unnecessary duplication of data is avoided.

DBMS allows a user to share the data in any number of application programs.

Integrity means that the data in the database is accurate. Centralized control of the
data helps in permitting the administrator to define integrity constraints to the data in
the database.

Having complete authority over the operational data enables the DBA to ensure that
the only means of access to the database is through proper channels. The DBA can
define authorization checks to be carried out whenever access to sensitive data is
attempted.

By eliminating data redundancy, we greatly reduce the opportunities for inconsistency.

In a database system, the data is managed by the DBMS and all access to the data is
through the DBMS providing a key to effective data processing.

With the centralized data, DBA can establish and enforce the data standards which
may include the naming conventions, data quality standards, etc.

When changes are made to the data representation, the metadata obtained by the
DBMS is changed but the DBMS continues to provide the data to the application
program in the previously used way.

DBMS supports many important functions that are common to many applications,
accessing data stored in the DBMS, which facilitates the quick development of
applications.

Disadvantages of DBMS

DBMS systems can be difficult to use, requiring special training and a steep learning
curve for new users. New users or people not from a technical background will find
navigating the system and using its various features and functions easier.
Because of this, you would be required to provide specialized training to your
employees, or else there will be a steep learning curve before they can use the system
to its full potential. And, because of the increased complexity, the system can be more
prone to errors. It will result in incorrect data being stored in the database.

The DBMS system may need help to handle increasing database size. Because of this
increase in database size, complexity will increase. And to decrease the complexity,
you might require additional resources, such as buying new faster processors, etc., to
overcome those problems. This can be a costly and time-consuming process.

is one of the biggest disadvantages of a database management
system. it requires a lot of maintenance and constant power. Data stored on DBMS is
centralized in nature, if the database server fails, the whole system will fail and the
organization will be affected

Performance issues are among the major disadvantages of DBMS because as a
database grows and complexity, it can slow down query speed and increase downtime.
This can result in decreased productivity and reduced efficiency, as users may have to
wait longer for their queries to be completed

is a collection of interrelated data and a set of programs that allow users
to access and modify these data

For the system to be usable, it must retrieve data efficiently. The need for efficiency has led
designers to use complex data structures to represent data in the database.

The lowest level of abstraction describes
how the data are actually stored. The physical level describes complex low-level data
structures in detail

The next-higher level of abstraction
describes what data are stored in the database, and what relationships exist among
those data. The logical level thus describes the entire database in terms of a small
number of relatively simple structures

The highest level of abstraction describes
only part of the entire database. Even though the logical level uses simpler structures,
complexity remains because of the variety of information stored in a large database.

The collection of
information stored in the database at a particular moment is called an

The overall design of the database is called the database

describes the database design at the physical level. A
Physical schema defines, how the data or information is stored physically in the
storage systems in the form of files & indices. The physical schema is hidden
beneath the logical schema and can usually be changed easily without affecting
application programs.

The logical schema describes the database design at the logical level. Of all
the types of schemas, the logical schema is by far the most important, in terms
of its effect on application programs, since programmers construct applications
by using the logical schema

A database may also have several schemas at the view level, sometimes called
subschemas, which describe different views of the database. It is a view level
design which is able to define the interaction between end-user and database.
User is able to interact with the database with the help of the interface without
knowing much about the stored mechanism of data in database.

A collection of conceptual tools for describing data, data relationships, data semantics, and
consistency constraints. A data model provides a way to describe the design of a database at
the physical, logical, and view levels.

Four different categories of Data Models

uses a collection of tables to represent both data and the
relationships among those data.

Tables
are also known as

are so named because the database is structured in
fixed-format records of several types

uses a collection of basic objects, called entities,
and relationships among these objects

is a “thing” or “object” in the real world that is distinguishable from other
objects. The entity relationship model is widely used in database design.

combines features of the object-oriented data model and
relational data model.

permits the specification of data where individual data
items of the same type may have different sets of attributes.

is widely used to represent semi structured data