dbms class
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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