Tuesday, April 1, 2014

Record based logical model

Record based logical model describe data at conceptual and view levels. They are used to provide  a logical structure of a database and also to give  a higher level description of the implementation.

Why named so?
1) It's named so because database is represented as fixed format records of several types
2) Each record type contain fixed number of fields or attributes

Three most widely accepted models are:
1) Relational model
2) Network Model
3) Hierarchical model

Comparison of these three models:
In network model data and relationships are represented using boxes and arrows. Each box represent a record type and each arrow represents a relationship. The hierarchical model is a specialization of network model where it consider a hierarchy in organizing record type. For example in hierarchical model College will be a parent record type for another record type Department. The Relational model represents data in a tabular format, with each row representing an entity of some type, and each column representing a defining attribute of the entity.

2 Comments:

At October 28, 2016 at 1:37 AM , Anonymous Anonymous said...

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