Database-MySQL [3i Infotech Placement]: Sample Questions 153 - 154 of 162

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Question 153

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Short Answer▾

What is Data Model?

Explanation

Data Models and Retional Data Model
  • A Data Model is a logical structure of Database.
  • It describes the design of database to reflect entities, attributes, relationship among data, constrains etc.

Types of data models:

Object based logical Models - Describe data at the conceptual and view levels.

  • E-R Model
  • Object Oriented Model

Question 154

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Describe in Detail

Essay▾

What is the job of the information stored in data-dictionary?

Explanation

  • The information in the data dictionary validates the existence of the object, provides access to them, and acts as actual physical storage location.
  • Not only RDBMS takes care of locating data it also determines an optimal access path to store or retrieve the data
  • A first step in analysing a system of objects with which users interact is to identify each object and its relationship to other objects.
  • This is called data modelling- a picture of object relationships.
  • Programs that use the data model, when developing a data dictionary can be consulted to understand where a data item fits in the structure, what values it may contain, and what the data item means in real world.
  • For example, a bank or group of banks could model the data objects involved in consumer banking. They could then provide a data dictionary for a bank՚s programmers.
  • The data dictionary would describe each of the data items in its data model for consumer banking.

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