Page 256 - DCAP405_SOFTWARE_ENGINEERING

Unit 14: Data Modeling

Hierarchical Data Model: A data model that organizes data into a tree-like structure where each Notes
node has a single parent node, the root node being an exception in the sense that it does not have
any parent.
Hierarchical Model: It is same as network model except that the records are rearrange in collection
of trees rather then arbitrary graph.

Network Data Model: A data model that views database as group of related items associated
with each other through links.
Network Model: In this model data is represented by collection of records and relationship with
links which can be thought of as pointers.
Physical Data Model: These are used to describe data at lowest level in contrast to logical data
model there are few physical model in use to of widely known once are unifying models and the
frame memory model.
Relational Model: This uses a collection of tables to represent both data and the relationship
among those data, each table has multiple column and each column has a unique name.

14.8 Review Questions

1. Describe the limitation that necessitated the design of different data models.

2. Compare and contrast between different data models.
3. Discuss the advantages and disadvantages of different data modeling techniques.
4. Differentiate between the network and hierarchical data models.
5. Write the following commands for the network data model.
(a) Insert an ID (=110) as a child of node (ID=103)

(b) Delete the node with ID(=008)
6. Convert the following E-R diagram into a structure of network data model.

7. Why do we require a mathematical model to design any system? Explain with examples.
8. What are the various techniques used to model data structure?
9. A hierarchical data model is a data model in which the data is organized into a tree-like
structure. Explain.
10. Multiple Choice Questions:
(i) A top-do-bottom relationship among the items in a database is established by a
(a) Hierarchical schema (b) Network schema

(c) Relational schema (d) All of the above

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