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Database Management System

(DBMS) Collection of interrelated data

Set of programs to access the data

DBMS contains information about a particular

enterprise Database Applications:

Banking: all transactions

Airlines: reservations, schedules

Universities: registration, grades

Sales: customers, products, purchases

Manufacturing: production, inventory, orders, supply chain

Human resources: employee records, salaries

Databases touch all aspects of our lives

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MetadataMetadata is defined as data about data. It describes theproperties and context of user data.

Name Type Length Min Max

Name Alphabets 30

Rollno Integer 6 6 6

What is a database?

It is an organized collection of logically related data .

Ex. the names, telephone numbers and addresses of all the

people you know

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DBMS

It is a collection of programs that enables user to

create and maintain a database. In other words it

is general-purpose software that provides theusers with the processes of defining,

constructing and manipulating the database for

various applications.

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Characteristics ofDBMS

Represents complex relationship between data

Controls data redundancy.

Enforces user defined rules.

Ensures data sharing.

It has automatic and intelligent backup and recoveryprocedures.

It has central dictionary to store information.

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ACID Test Atomicity

Consistency

Isolation

Durability

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D

atabase Arch

itecture

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External View

User View 1 User view 2

Customer

name

Customer

city

Customer

BalanceCustomer

name

Customer city

Conceptual ViewCUSTOMER

Customer ID: integer(4)

Customer Name:String(20)

Customer Street:String(40)

Customer City:String(10)

Customer Balance:integer(8)

Internal View

CUSTOMER

Customer ID: 4 decimal offset 0 unique

Customer Name:String length 20 offset 4

Customer Street: String length 40 offset 4

Customer City: String length 10 offset 64

Customer Balance:8,2 dec offset 74

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Advantages of DBMS Control of data redundancy

Data consistency

Sharing of data

Improved data integrity

Improved maintenance through data

independence.

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Disadvantages of DBMS Complexity

Cost of DBMS

Cost of conversion

Performance

Higher impact of a failure

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Relational DBMS Based on Relational Mathematics principles

Data is represented in terms of rows and

columns of a table

Addresses all types of relations

Easy to design

No anomalies for insert/delete/update

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Database & RDBMS concepts RELATIONAL MODEL

Tuple

Attribute

RelationEMPNO FIRSTNME Age WORKDEPT

10 Ananya 25 A00

20 Swetha 32 B01

30 Prashanth 55 C01

Relation :: Table

Tuple :: Row

Attribute :: Column

Domain :: Range ofvalues for an attribute

Primary

Key

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Relational Database Model

department location

A00 Chennai

C01 Hyderabad

B01 Pune

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Relational TerminologyTuple (Row)

Attribute (Column)

Relation (Table)

Integrity Constraints

Primary KeyForeign Key

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Database & RDBMS concepts: Terminology

PRIMARY KEY: Column used to uniquely identify aTuple

COMPOSITE KEY: A combination of columns used to

identify a unique row.C

ombination of customer nameand address can consider to be the composite key of thecustomer table.

ALTERNATE KEY: Column or combination of

columns whichhas unique values but not selected asprimary key and is not part of the primary key.

FOREIGN KEY: Column of a table used to establishrelationship with other tables and present itself in allthe relation tables.

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Structured Query Language

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Structured Query Language DDL Data Definition Language

DML Data Manipulation language

DCL Data Control Language

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DDL Create

Alter

Drop

Truncate

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DML Insert

Update

Delete

Select

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DCL Commit

Rollback

Save point

Set transaction

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Integrity Constraints Primary key (PK)

Foreign Key (FK)

Unique key (UK)

Not Null

Check

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Object Oriented Database

Management System(OODBMS)

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What is an object?

Tangible Things as a car, printer, ...

Roles as employee, boss, ...

Incidents as flight, overflow, ...

Interactions as contract, sale, ...

Specifications as colour, shape,

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The two parts of an objectObject = Data + Methods

or to say the same differently:

An object has the responsibility to know and

the responsibility to do.

= +

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Example: A Rabbit object You could (in a game, for example) create

an object representing a rabbit

It would have data: How hungry it is

How frightened it is

W

here it is And methods:

eat, hide, run, dig

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Basic Terminology Abstraction is the representation of the

essential features of an object. These are

encapsulated into an abstract data type. Encapsulation is the practice of including in an

object everything it needs hidden from other

objects. The internal state is usually notaccessible by other objects.

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Basic Terminology:

Polymorphism Polymorphism means having many

forms. It allows different objects to

respond to the same message in differentways, the response specific to the type of

the object.

E.g. the message displayDetails() of thePerson class should give different resultswhen send to a Student object (e.g. theenrolment number).

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Basic Terminology:

Inheritance Inheritance means that one class inherits the

characteristics of another class.

This is also called a is a relationship:

A car is a vehicle

A teacher is a person

Adog is an animal

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OODBMS and RDBMS

OODBMS RDBMS

Object Entity

Data Encapsulation and Dataindependence Data Independence

OODBMS store data and

methods.

RDBMS store only data.

Object Identifier (OID) Primary Key

Complex Data Simple Data

Inheritance None