Relational Database Management System : All required Study notes

Hello guys, today in this article we are going to discuss on Database Management System (DBMS). In this article, we will try to cover all the basic terms that are related to Database (DB) and Database Management System (DBMS).

Database (DB) and Database Management System (DBMS) :

Architecture of RDBMS
RDBMS Structure


Database:

 It is a repository or contains for a collection for a collection of computerized data files in the form of tables, Schemas or views. Users of the system can perform several operations on those files such as:

  • Adding new files (CREATE).
  • Inserting data on files (INSERT).
  • Retrieving data from files (SELECT).
  • Deleting data from files (DELETE).
  • Removing files (DROP).

DBMS:

In a system software which manages and organizes data & data files in a systematic way such that it can be accessed, retrieve and modify (Update). whenever the user thinks it is necessary. DBMS manages three things.
  • Data
  • Database Engine
  • Database Schema

General Structure of DBMS:



General Structure of Database Management System




Types of DBMS:
  • Relational Database Management System (RDBMS)
  • Distributed RDBMS
  • Cloud RDBMS
  • NoSQL RDBMS
  • Columnar RDBMS
Here, we will mainly focus on RDBMS whatever we study in this course will be associated with RDBMS.

Advantages of DBMS:
  • Data management and Organization.
  • Easier to access retrieve and update whenever necessary.
  • Data reusability.
  • Data abstraction.
  • Data Security.

DBMS Architecture:-

The design of DBMS depends on it's an architecture which can be centralized, Decentralized or hierarchical. The architecture of DBMS can be seen either is single or multi-tier.

1-Tier Architecture: In 1-tier architecture all the components required to run an application/software are kept on a single server platform. 

one-tier Architecture
1-Tier Architecture



2-Tier Architecture: 2-tier architecture is a client-server architecture direct communication takes place between client and DB server.

two-tier Architecture
2-Tier Architecture


3-Tier Architecture: It is the mostly used architecture used architecture to design DBMS. The main objective of 3-tier architecture is to obtain data independence.


three-tier Architecture
3-Tier Architecture


Now we are going to elaborate on 3-tier architecture:
  • External Schema (How data looks like): This is the schema which can be viewed by users application. It is the topmost DBMS architecture.

  • Logical Schema (What data is stored and their relationship): This is the logical organization of DB. It represents a logical data structure through Which application can access the DB. It resides in the middle layer as a business logic layer (BLL). acts as a mediator between end users and DB.


  • Data Abstraction: Data abstraction means hiding of data on the lower layer to the upper layer. It means maintaining confidentiality over data. Developers of the DB system hides internal Irrelevant and complex data structures from users, which is called data abstraction.

  • Data Independence: It is an ability to modify a schema definition in one level/layer without affecting a schema definition in the next layer. The three-tier architecture allows the facility of data independence.

  • Physical Data Independence: 
    • It indicates that changes in the physical schema (structures/ definition of physical storage ) do not affect logical schema.
    • It is easy to achieve physical data independence separates the conceptual level from the physical level.

Logical Data Independence:

    • It indicates that changes in the logical schema can be one without changing the external schema. In other words, change in logical/conceptual schema does not affect external schema.
    • Comperatively it is difficult to achive logical schema. 
    • Logical data independence seperates external level from logical view.



I hope you find it easier than ever to understand on Database Management System. See you guys on next article.
  

Relational Database Management System : All required Study notes Relational Database Management System : All required Study notes Reviewed by ElightTechnical on December 11, 2018 Rating: 5

No comments:

Powered by Blogger.