DAN 613 - Computer Applications 2013-14

8/13/2019 DAN 613 - Computer Applications 2013-14

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S


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DBMS Bene

Improved strategic use of corporate data

Reduced complexity of the organizationinformation systems environment

Reduced data redundancy and inconsisten

Enhanced data integrity

Application-data independence

Improved security

DBMS B f


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DBMS Benef

Reduced application development andmaintenance costs

Improved flexibility of information systems

Increased access and availability of data andinformation

Logical & Physical data independence

Concurrent access anomalies

Facilitate atomicity problem

Provides central control on the system through D


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Data Hierarchy

Database Collection of

interrelated data

File A group of

interrelated records

Record

Field

Byte Bit

Personal

Data file

Credit

History file

Transaction

Data file

Last Name

Shetty

First Name

Lalith

Address

89 A, Block II

Manipal

Phone no

29282833

Shetty Lalith 89 A, Block II

Manipal

29282833

L a l i t h

Last Name First Name Address Phone no

0 or 1


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Salesmanrecord

CustomRecor

Accrece

Salesstatistics

record


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Hierarchical Model

This helps to establish explicit or logicalrelationship among various data elemen

of multiple files

Each BOX is referred record also called aa node

Record that has subsidiary records calleas PARENT

SUBSIDIARY called as CHILD


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R l ti l M d l


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Relational Model

A relational database allows the definition

data structures, storage and retrieval

operations and integrity constraints.

In such a database the data and relationsbetween them are organised in tables.

A table is a collection of records and each

record in a table contains the same fields.


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Oracle

DB2

Sybase Adaptive

Server Enterprise

FileMaker

Firebird

Ingres

Informix

Microsoft Access

Relational


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Relational In the relational data model, the data

database is organized in relations. A relatio

synonymous with a table.

A relational database is a database conforms to the relational model, and refers

database's data and schema (the databastructure of how those data are arranged).

The term "relational database is sometiinformally used to refer to a relational datab

management system, which is the software th

used to create and use a relational database

Keys


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Keys

Primary Key: A unique key is a kind of constrainthat ensures that an object, or critical informatio

about the object, occurs in at most one tuple in a

given relation

Foreign key is a reference to a key in anotherrelation, meaning that the referencing Tuple has

one of its attributes, the values of a key in the

referenced tuple

Documents

DAN 613 - Computer Applications 2013-14