LECTURE 1

INT 306
Database Management System
What is Data?

• DATA- RAW Facts

• The facts that have not been processed to explain their meaning.
• Data is a collection of a distinct small unit of information. It can be used in a
variety of forms like text, numbers, media, bytes, etc. it can be stored in pieces of
paper or electronic memory, etc.
• In computing, Data is information that can be translated into a form for efficient
movement and processing. Data is interchangeable.
 Difference Between Data and Information ?

• Data is an individual unit that contains raw material which does not carry any specific
meaning. 
• Information is a processed, organised data presented in a given context and is useful to
humans. 
• Information is a group of data that collectively carry a logical meaning
 Database
• A database is an organized collection of data, so that it can be easily accessed , process, and managed.
• You can organize data into tables, rows, columns, and index it to make it easier to find relevant
information.
• Database handlers create a database in such a way that only one set of software program provides
access of data to all the users.
• The main purpose of the database is to operate a large amount of information by storing, retrieving,
and managing data.
• There are many dynamic websites on the World Wide Web nowadays which are handled through
databases.
• For example, a model that checks the availability of rooms in a hotel. It is an example of a dynamic website
that uses a database.
• There are many databases available like MySQL, Sybase, Oracle, MongoDB, Informix, PostgreSQL, SQL
Server, etc.
Database
• Modern databases are managed by the database management system (DBMS).
• SQL or Structured Query Language is used to operate on the data stored in a database.
• SQL depends on relational algebra and tuple relational calculus.
• EndUser data: (raw facts of interest to user about products)
• MetaData: (Description about data to expand value and use to data)
Difference between File System and DBMS

• File System Approach

• File based systems were an early attempt to
computerize the manual system.
• It is also called a traditional based approach in
which a decentralized approach was taken
where each department stored and controlled
its own data with the help of a data processing
specialist.
• The main role of a data processing specialist was
to create the necessary computer file structures,
and also manage the data within structures and
design some application programs that create
reports based on file data.
DBMS:

• A database approach is a well-organized collection

of data that are related in a meaningful way which
can be accessed by different users but stored only
once in a system.
• The various operations performed by the DBMS
system are: Insertion, deletion, selection, sorting
etc.
Difference between DBMS and File systems
Basis DBMS Approach File System Approach
Meaning DBMS is a collection of data. In The file system is a collection of
DBMS, the user is not required data. In this system, the user has
to write the procedures. to write the procedures for
managing the database.
Sharing of data Due to the centralized approach, Data is distributed in many files,
data sharing is easy. and it may be of different
formats, so it isn't easy to share
data.

Data DBMS gives an abstract view of The file system provides the
Abstraction data that hides the details. detail of the data
representation and storage of
data.
Security and DBMS provides a good It isn't easy to protect a file
Protection protection mechanism. under the file system.
Recovery Mechanism DBMS provides a crash recovery mechanism, i.e., The file system doesn't have a crash mechanism,
DBMS protects the user from system failure. i.e., if the system crashes while entering some
data, then the content of the file will be lost.

Manipulation DBMS contains a wide variety of sophisticated The file system can't efficiently store and retrieve
Techniques techniques to store and retrieve the data. the data.

Concurrency Problems DBMS takes care of Concurrent access of data In the File system, concurrent access has many
using some form of locking. problems like redirecting the file while deleting
some information or updating some information.

Where to use Database approach used in large systems which File system approach used in large systems which
interrelate many files. interrelate many files.

Cost The database system is expensive to design. The file system approach is cheaper to design.
Data Redundancy and Due to the centralization of the database, the In this, the files and application programs are
Inconsistency problems of data redundancy and inconsistency created by different programmers so that there
are controlled. exists a lot of duplication of data which may lead
to inconsistency.

Structure The database structure is complex to design. The file system approach has a simple structure.

Data Independence In this system, Data Independence exists, and it In the File system approach, there exists no Data
can be of two types. Independence.
o Logical Data Independence

o Physical Data Independence

Integrity Constraints Integrity Constraints are easy to apply. Integrity Constraints are difficult to implement
in file system.

Data Models In the database approach, 3 types of data models In the file system approach, there is no concept
exist: of data models exists.
o Hierarchal data models

o Network data models

o Relational data models

Flexibility Changes are often a necessity to the content of The flexibility of the system is less as compared
the data stored in any system, and these changes to the DBMS approach.
are more easily with a database approach.
Difference between DBMS and RDBMS

DBMS RDBMS

DBMS applications store data as file. RDBMS applications store data in a tabular form.

In DBMS, data is generally stored in either a hierarchical form In RDBMS, the tables have an identifier called primary key and
or a navigational form. the data values are stored in the form of tables.

Normalization is not present in DBMS. Normalization is present in RDBMS.

DBMS does not apply any security with regards to data RDBMS defines the integrity constraint for the purpose of
manipulation. ACID (Atomocity, Consistency, Isolation and Durability)
property.

DBMS uses file system to store data, so there will be no in RDBMS, data values are stored in the form of tables, so
relation between the tables. a relationship between these data values will be stored in the
form of a table as well.
DBMS uses file system to store data, so there will be no in RDBMS, data values are stored in the form of tables, so
relation between the tables. a relationship between these data values will be stored in the
form of a table as well.

DBMS has to provide some uniform methods to access the RDBMS system supports a tabular structure of the data and a
stored information. relationship between them to access the stored information.

DBMS does not support distributed database. RDBMS supports distributed database.

DBMS is meant to be for small organization and deal with small RDBMS is designed to handle large amount of data. it
data. it supports single user. supports multiple users.

Examples of DBMS are file systems, xml etc. Example of RDBMS are mysql, postgre, sql server, oracle etc.

Evolution of Databases

• The database has completed more than 50 years of journey of its evolution from flat-file system to
relational and objects relational systems.
• File-Based
• Hierarchical Data Model
• Network data model
• The Object-Oriented Databases
• RDBMS (Relational Database Management System)
• E-R Model
file-based databases Databases

• 1968 was the year when File-Based database were introduced.

• In file-based databases, data was maintained in a flat file.
• Though files have many advantages, there are several limitations.
• One of the major advantages is that the file system has various access methods, e.g., sequential,
indexed, and random.
• It requires extensive programming in a third-generation language such as COBOL, BASIC.
Hierarchical Data Model
• 1968-1980 was the era of the Hierarchical
Database. Prominent hierarchical database model
was IBM's first DBMS. It was called IMS
(Information Management System).
• In this model, files are related in a parent/child
manner.
• Below diagram represents Hierarchical Data
Model. Small circle represents objects.
• Like file system, this model also had some
limitations like complex implementation, lack
structural independence, can't easily handle a
many-many relationship, etc.
Network data model

• Charles Bachman developed the first DBMS at Honeywell called Integrated Data Store (IDS). It was
developed in the early 1960s, but it was standardized in 1971 by the CODASYL group (Conference
on Data Systems Languages).
• In this model, files are related as owners and members, like to the common network model.
• Network data model identified the following components:
• Network schema (Database organization)
• Sub-schema (views of database per user)
• Data management language (procedural)
• This model also had some limitations like system complexity and difficult to design and maintain.
Relational Database
• 1970 - Present: It is the era of Relational Database and Database Management. In 1970, the
relational model was proposed by E.F. Codd.
• Relational database model has two main terminologies called instance and schema.
• The instance is a table with rows or columns
• Schema specifies the structure like name of the relation, type of each column and name.
• This model uses some mathematical concept like set theory and predicate logic.
• The first internet database application had been created in 1995.
• During the era of the relational database, many more models had introduced like object-oriented
model, object-relational model, etc.
RDBMS (Relational Database Management
System)
• The word RDBMS is termed as 'Relational Database Management System.' It is represented as a
table that contains rows and column.
• RDBMS is based on the Relational model; it was introduced by E. F. Codd.
• A relational database contains the following components:
• Table
• Record/ Tuple
• Field/Column name /Attribute
• Instance
• Schema
• Keys
• An RDBMS is a tabular DBMS that maintains the security, integrity, accuracy, and consistency of the
data.
Data Models
• Hierarchical data model: This is called a parent-child
relationship. In this model each entity has only one parent but
several children. At the top of the hierarchy there is only one
entity which is called Root.
Data Models
• Network model: In a network DBMS every data item
can be related to many others ones. The database
structure is like a graph. This is similar to the
hierarchical model and also provides a tree-like
structure. However, a child is allowed to have more
than one parent.
Data Models
• Relational data model: In relational data model,
data exists in two dimensional tables known as
relations. A relation (table) consists of unique
attributes (columns) and tuples (rows).
Data Models
• Object oriented model: Object based data models
use concepts such as entities, attributes, and
relationships
• The entity relational model( E-R model) has emerged
as one of the main techniques for modeling database
design .