KULDEEP DBms

8/7/2019 KULDEEP DBms

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PRESENTED BY :KULDEEP YADAV

SECTION A

REG . NO T- 6024

PGDM - 2010-12

GROUP NO 4


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DATA MODELS :

It is a representation of the real world objectsand their associations. It provides the basic

concepts and notations for understanding the

organizational data. Used for representing theentities and their relationships in the database.

It consists of

Static properties like objects, attributes and relationshipsIntegrity rules over objects and operations.

Dynamic properties like operations or rules defining new

database states based on applied state changes.


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TYPES OF DATA MODELS :

Data models can be

Record-based models

Object-based models

Physical based models

Record-based data models :

The database consists of a number of fixed-formatrecords of different types having a fixed number of fieldsand each typically of fixed length. Types are

Hierarchical model

Network model

Relational model


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THE RELATIONAL MODEL

Developed by Codd (IBM) in 1970

Considered ingenious but impractical in 1970

Conceptually simple

Computers lacked power to implement the

relational model

Today, microcomputers can run sophisticated

relational database software

RELATIONAL DATA MODEL


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HIERARCHICAL DATA MODEL

Represented by an upside-down tree.

Database as a hierarchy of segments.( A file systems recordtype or levels)

Based on parent_child relationship.

Shows one-to-many relationship between entities where the two

must be parent and child.

A

B C

ED

Level 0 : Root Parent

(node)

Level 1 : Root Children(segment)

Level 2 : Segments

(Level-1 children)


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HIERARCHICAL DATA MODEL

Follows the left-traced path. Ex : The hierarchical path for

segment E can be traced as ABDE. ( preorder traversal or

hierarchical sequence )

University

Department

DEPT-CODE DEPT-NAME DEPT-LOCATION

Faculty

FCLTY_NO FCLTY_NAME

FCLTY_SALARY

Course

COURSE_CODE COURSE_TITLE


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NETWORKDATA MODEL

Similar to hierarchical model except that a record can have

multiple parents.The relationship is called a set.

The first record type is the owner and the second as the member.

Facilitates many-to-many relationship.

vc vv

A

B C

D E F


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NETWORKDATA MODEL

SALES_REPRESENTATIV

ECUSTOMER

INVOICE PAYMENT

1:m 1:m 1:m


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Object-based data models :Uses concepts like objects, attributes and relationships. Types are

Entity-relationship

Semantic

Functional

Object-oriented

Physical data models :Used for a higher level description of storage structure and accessmechanism.

Describe how data is stored in the computer, representing informationsuch as record structures, record orderings and access paths.

Types are

Unifying model

Frame memory model


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KULDEEP DBms

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