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Data can be organised into two types:
Flat File: Data is stored in a single table. It is mainly suitable for less volume of data.
Relational: In relational files, data is stored in multiple tables and the tables are linked using a common
field. Relational is suitable for medium to large volumes of data.
Database Servers
Database servers are dedicated computers designed to store and manage databases. These servers typically
run the Database Management System (DBMS) software along with its related applications. Databases hosted
on database servers can be accessed through command-line tools or Graphical User Interface (GUI) tools,
which are often referred to as frontends. In a typical client-server architecture, the database servers act as
backends that process requests and provide data to the client applications (frontends).
Notes
Who governs the Database Management System?
The person having the centralised control over the database system is called the Database Administrator.
The database administrator is an IT expert who is responsible for the technical operations and management
of database for ensuring its smooth functioning.
DATA MODEL
A data model is a conceptual representation of data structures and relationships that helps in organising
and understanding the data. It defines how data is stored, processed and accessed within a database system.
There are several types of data models:
Hierarchical Data Model
The Hierarchical Data Model organises data in a tree-like structure similar to a family tree. At the top is a
single parent node, and beneath it are child nodes, which can further have their own children. Data is stored
in records, each consisting of fields and their corresponding data values. These records are interconnected
at different levels, forming a hierarchical structure. This can be likened to organising files and folders on a
computer, where each folder may contain multiple files or subfolders.
Although straightforward in structure and navigation, this model can become inflexible and difficult to modify
as data relationships evolve.
The hierarchical data model consists of interconnected nodes, each connected by branches:
Nodes are organised in a tree-like structure with branches linking them.
The topmost node is called the root node, serving as the starting point of the hierarchy.
If there are multiple nodes at the top level, they are referred to as root segments.
Each node has exactly one parent, which is the node directly above it in the hierarchy.
A parent node can have multiple child nodes branching out from it.
The model ensures a clear, nested relationship where nodes are organised hierarchically based on their
parent-child connections.
It supports efficient storage and retrieval of information similar to organising files and folders on a
computer, where folders (parents) contain files and subfolders (children).
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