Data Modelling & SQL Language

Running head: DATA MODELLING & SQL LANGUAGE
Data Modelling & SQL Language
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DATA MODELLING & SQL LANGUAGE1
Table of Contents
Task 1: Understanding of Database.................................................................................................2
1.1Database System VS File Based System:...............................................................................2
1.2 Hierarchical, Network and Relational Models:.....................................................................3
1.3 Top-down and Bottom-up Approaches:................................................................................4
Task 2: Conceptual Modelling.........................................................................................................5
Task 3: Logical Modelling...............................................................................................................6
Task 4: Physical Modelling...........................................................................................................13
Create Database:........................................................................................................................13
Bibliography:.................................................................................................................................18

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Task 1: Understanding of Database
1.1Database System VS File Based System:
Database System: The database management system is a set of data. In terms of database
management system, there is no need to write procedures. The database management system
offers an abstract view of data. This allows the database management system to offer the user
access to data without providing insight of it. There is also a crash recovery mechanism in
database management system which is safeguards the data from system failure. There is also
very good protection mechanism in database management system. The storing and retrieval of
data is done in organized way in database management system (Arulraj 2017). There is also
locking approaches in database management system which handles the concurrent access of data.
The main advantage of database system is synchronization. The data will be
synchronized within the database so that every transaction data can be handled properly. The
disadvantage of database management system is ineffective memory usage. The consistent usage
of RAM can make the system slow. The biggest limitation of DBMS is cost. The database
system are costly than file based system.
File Based System: The file system is also a collection of data, however, which asks the
user to write various procedures for handling the data. The representation and storage of data is
provided by the file based system. File system does not include any approach for protecting the
data from system failure as it does not have any crash mechanism. This can be a huge issue as all
the data can be lost.
The first advantage of file based system is saving the data. The data can be saved by just
one click. The data migration in file based system is also very easy (Arpaci-Dusseau, Arpaci-
Dusseau and Venkataramani 2018). The disadvantage is that there is no complex ideas like
ACID property in file based system. The main limitation of this system is data duplication.
Advantages of DBMS over File Based System: The database management system is
capable of managing data redundancy. The redundancy is the concept of data repetition which
creates multiple copies of same data. There is no approach in the file based system to manage the
redundancy of data. The sharing of data is very complex in file based system. However, as the

DATA MODELLING & SQL LANGUAGE3
database system has centralized approach, the sharing of data is very easy. In order to perform a
search operation, different programs needs to be developed. The database management system
provides a very easy approach toward searching by providing inbuilt searching option.
1.2 Hierarchical, Network and Relational Models:
Hierarchical Model: A tree like structure is used in the hierarchical database model for
each record that has one parent and many children. The hierarchical model supports only one-to-
many relationship between parent and child nodes.
Taken as an example, the students can be direct children of the root node. Each course
can be children of student node (Ogle et al. 2016). The above model describes that one student
can have many courses. This means that a children can also have many children and in that case
that particular child node will function as parent node.
Network Model: The network data model is designed for representing the objects and the
relationship among the objects flexibly. The schema in the network model is represented as the
graph. The objects are interpreted as nodes and relationships are viewed as arcs. The concept
behind the network model is very simple and implementation of network model is also effortless
(Gile and Handcock 2015). The network model is capable of handling many-to-many and one-to-