Data Modelling and SQL Language

Running head: DATA MODELLING AND SQL LANGUAGE
Data Modelling & SQL Language
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DATA MODELLING AND SQL LANGUAGE
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Task 1
Comparison of the File based system and database system
Advantages and Disadvantages of File based system
Easy Backup: in case of the file based data storage system it is possible have faster
back-up of the stored data in the computer-based information systems. There are numerous
functionalities available for Computer based information systems that are helpful in the
accomplishing this purpose. Moreover it is also possible to develop applications that are
tailored for specific purposes.
Compactness: In file based systems it is also possible to store required data in a
compact way so that the memory or disk usage can be minimized.
Retrieval and editing of information: Computer-based file systems are very
helpful in the providing different data retrieval techniques or editing techniques which are
easy and efficient for managing the data stored in file format.
Disadvantages of file based system
In case of the file based system following are the most important disadvantages,
Redundancy of data: in case of file based system it may happen that the users
possibly store the same data/information multiple times which will lead to duplicated storage
and additional storage requirements and hence leads to the memory wastage.
Inconsistent Data: As the file based systems are prone to data redundancy thus it may
lead to the data that are not in a consistent state.
Accessibility issues to the Data: Accessibility to the data is not that much convenient
when data is stored inside a file processing system.

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Advantages of the Database system
Compared to the traditional file based system of data storage following are the
advantages that encourages the users to use DBMS system rather than the File based system.
Consistency and Integrity of Data: As it is found that the main reason behind the data
inconsistency is data redundancy thus use of the normalization while storing data in the
DBMS takes care and resolves the data redundancy issue. In the same manner the data
inconsistency issue is also resolved through the maintenance of the ACID property of any
database.
Data Security: In database system it is possible to apply access constraints depending
on the authorization level in database systems. In this way, it can be ensured that only the
authorized users can access to some specific section of data. Different users may have
different level of access rights there making the data secured in such way that the stored data
can be secured from different issues data leaks or misuse of data.
Disadvantages of Database system
Compared to the file based system different DBMS implementation projects cost
much higher than the file system
Complexity of the implementation and usability: DBMS are complex in nature and
new users may feel hard to determine the usability and functionality.
Performance of the databases: Most of the DBMS are generic in nature which
makes this solutions suitable for different applications. However in certain scenarios this
generic nature adversely affects the performance for the users.

DATA MODELLING AND SQL LANGUAGE
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Characteristics of the of Hierarchical, network and relational
database models
Hierarchical model
For hierarchical model, the data is stored in tree like structures where the parent child
relationship is maintained. In other words it can be stated that required data is saved in top
down or bottom up approach. Data stored in the database is represented in the form of parent-
child relationship. In this kind of database system parent can have multiple children, whereas
the children can have only one parent.
Network models
In case of the network database model, it allows the child to have multiple parents
while storing data in the databases. In this way, it helps the users in order to address the need
to model and support very complex relationships between the different database entities such
as the many-to-many relationships among the different related tables. In the Network based
model, the tables /entities are managed through the use of a graph that can be accessed for
data retrieval through the use of the several paths connecting to the parent and child nodes.
Relational database
The Relational database model is the most popular model that is used in the industry
or users. This database model is normalizes data in the forms of row (records) and columns
(Attributes) of the tables inside the database. In case of the Relational model the data is
stored in predetermined structures and manipulated through the use of the SQL or the
structured query language.