Introduction to DBMS
Contents:
• Concept of Data
• Database
• DBMS
• Types of Data Models
• Types of DBMS
• File system Vs DBMS
• Database users
• 3T Database architecture
• Data Independence
• Purpose of Database System
• Database Language
What is data?
• In common usage and statistics, data is a collection of discrete or
continuous values that convey information, describing the quantity,
quality, fact, statistics, other basic units of meaning, or simply
sequences of symbols that may be further interpreted formally.
What is Database?
• A database is an organized collection of structured information, or
data, typically stored electronically in a computer system. Data within
the most common types of databases in operation today is typically
modeled in rows and columns in a series of tables to make processing
and data querying efficient. The data can then be easily accessed,
managed, modified, updated, controlled, and organized. Most
databases use structured query language (SQL) for writing and
querying data.
What is DBMS?
• A database is usually controlled by a database management system (DBMS).
Together, the data and the DBMS, along with the applications that are associated
with them, are referred to as a database system, often shortened to just database.
• A database typically requires a comprehensive database software program known
as a database management system (DBMS). A DBMS serves as an interface
between the database and its end users or programs, allowing users to retrieve,
update, and manage how the information is organized and optimized. A DBMS
also facilitates oversight and control of databases, enabling a variety of
administrative operations such as performance monitoring, tuning, and backup and
recovery.
• Some examples of popular database software or DBMSs include MySQL,
Microsoft Access, Microsoft SQL Server, FileMaker Pro, Oracle Database, and
dBASE.
What is a MySQL database?
• MySQL is an open source relational database management system based
on SQL. It was designed and optimized for web applications and can run on
any platform. As new and different requirements emerged with the
internet, MySQL became the platform of choice for web developers and
web-based applications. Because it’s designed to process millions of
queries and thousands of transactions, MySQL is a popular choice for
ecommerce businesses that need to manage multiple money transfers. On-
demand flexibility is the primary feature of MySQL.
• MySQL is the DBMS behind some of the top websites and web-based
applications in the world, including Airbnb, Uber, LinkedIn, Facebook,
Twitter, and YouTube.
Example of Hierarchical model
Example of Relational database
• In the above student table Std ID, Name and city are called as
attributes and their values. Std ID is a primary key attribute which
uniquely identifies each record in the student table.
The object oriented database is represented
in diagram format below −
Types of DBMS
The types of DBMS based on data model are as follows −
Relational database.
Object oriented database.
Hierarchical database.
Network database.
Basis DBMS Approach File System Approach
The file system is a collection of data. In this
DBMS is a collection of data. In DBMS, the user is
Meaning system, the user has to write the procedures for
not required to write the procedures.
managing the database.
Due to the centralized approach, data sharing is Data is distributed in many files, and it may be of
Sharing of data
easy. different formats, so it isn't easy to share data.
DBMS gives an abstract view of data that hides the The file system provides the detail of the data
Data Abstraction
details. representation and storage of data.
Security and Protection DBMS provides a good protection mechanism. It isn't easy to protect a file under the file system.
The file system doesn't have a crash mechanism,
DBMS provides a crash recovery mechanism, i.e.,
Recovery Mechanism i.e., if the system crashes while entering some data,
DBMS protects the user from system failure.
then the content of the file will be lost.
DBMS contains a wide variety of sophisticated The file system can't efficiently store and retrieve
Manipulation Techniques
techniques to store and retrieve the data. the data.
In the File system, concurrent access has many
DBMS takes care of Concurrent access of data
Concurrency Problems problems like redirecting the file while deleting
using some form of locking.
some information or updating some information.
Database approach used in large systems which File system approach used in large systems which
Where to use
interrelate many files. interrelate many files.
Cost The database system is expensive to design. The file system approach is cheaper to design.
In this, the files and application programs are
Due to the centralization of the database, the
created by different programmers so that there exists
Data Redundancy and Inconsistency problems of data redundancy and inconsistency are
a lot of duplication of data which may lead to
controlled.
inconsistency.
Structure The database structure is complex to design. The file system approach has a simple structure.
•In this system, Data Independence exists, and it can
In the File system approach, there exists no Data
Data Independence be of two types. Logical Data Independence
Independence.
•Physical Data Independence
Integrity Constraints are difficult to implement in file
Integrity Constraints Integrity Constraints are easy to apply.
system.
•In the database approach, 3 types of data models
exist: Hierarchal data models In the file system approach, there is no concept of
Data Models
•Network data models data models exists.
•Relational data models
Changes are often a necessity to the content of the
The flexibility of the system is less as compared to the
Flexibility data stored in any system, and these changes are
DBMS approach.
more easily with a database approach.
Examples Oracle, SQL Server, Sybase etc. Cobol, C++ etc.
Database Users
Database users can be divided into the following types −
End Users
Naive users / Parametric users
Sophisticated users
Application Programmer or Specialized users or Back-End Developer
System Analyst
Database Administrator (DBA)
Temporary Users or Casual Users
End Users/Parametric Users − These users access the database from the front end with the help of a pre-developed application.
They have little knowledge about the design and working of databases.
There are two types of end users −
Naive Users − These naive users are those users who don’t have any database knowledge. They depend on pre-developed
applications like Bank Management Systems, Library Management Systems, Hospital Management Systems, and Railway Ticket
Booking Systems(IRCTC) and get the desired result.
Sophisticated Users − These users interact with the system without writing a program and have separate databases for personal
use. In the database, the user passes each query to the query processor.
• There are two ways to interact with a system −
• They use the structure query language to run the query on the database.
• They use the tool of data analysis software. For example, data engineers and data scientists are familiar with databases.
Application programmers/Specialized programmers/Back-End Developer − These programmers write the
code for an application program that uses the database. The application programmer can make the
application according to user requirements and control software that runs an entire computer system. The
application program is written in any programming language like C#, .net, JAVA, etc., and focuses on
business, engineering, and science program.
Application Programmers are divided into four different types −
Web Developers
Computer Hardware Programmers
Database Developers
Software Developers
Examples of Application programmers develop software like −
• Content access software
• Educational Software
• Information Worker Software
• Media Development Software
• Product Engineering Software
• Enterprise Software
System Analyst − A System Analyst has also known as a business technology analyst. These
professionals are responsible for the design, structure, and properties of databases. The
application programmer uses the specifications provided by the system analyst to construct the
software that is used by end users. The analyst will gather information from the shareholders as
well as end users to understand their requirements and translate it into functional specifications
for the new system.
Examples of System Analysts −
They serve as team leaders.
They are responsible for managing projects.
They are the supervisor who manages the lower-level information Staff.
Database Administrator (DBA) − The DBA is the group of people that includes everything
required to manage and solve every complex. The DBA can easily use the database to
find the information they need and to plan the goal of the database. To meet future
needs, they are ready for future scope and provide solutions for end users. Therefore,
they are known for high-level management.
For example −
To handle the data loss.
To secure the privacy of data.
Monitor the recovery and backup of the database.
Temporary Users/Casual Users − These users utilize the database for
testing and are only accessible for a limited time. According to
business requirements, these users update a little or new information
to the database with the help of a database administrator. It helps to
maintain the security and integrity of data.
For example
High-level management people are temporary users with little
knowledge of DBMS.
Types of DBMS Architecture
3-Tier Architecture
• The 3-Tier architecture contains another layer between the client and
server. In this architecture, client can't directly communicate with the
server.
• The application on the client-end interacts with an application server
which further communicates with the database system.
• End user has no idea about the existence of the database beyond the
application server. The database also has no idea about any other
user beyond the application.
• The 3-Tier architecture is used in case of large web application.
Data Independence
• Data Independence is defined as a property of DBMS that helps you
to change the Database schema at one level of a database system
without requiring to change the schema at the next higher level. Data
independence helps you to keep data separated from all programs
that make use of it.
• You can use this stored data for computing and presentation. In many
systems, data independence is an essential function for components
of the system.
Purpose of Database System
1. Efficient storage and retrieval
2. Protecting confidential data
3. Database systems prioritize the security of sensitive data
4. Data backups and transaction management
Database Language
• Database language refers to the specific types of commands or
instructions used to communicate with a database. It helps users or
applications to create, manage, update, and retrieve data from a database.
database language is like a set of tools that help you talk to and work with
the data stored in a database.
• Types of Database Languages in DBMS
• There are different types of database languages, including DDL, DCL, DML,
and TCL. Each category language is used for a different purpose Below I
explain each category with proper examples.
•
DDL (Data Definition Language)
• The DDL stands for Data Definition Language, Which is used to define
the database's internal structure and Pattern of the Database.
• The DDL is used for creating tables, indexes, constraints, and schema
in the Database.
• By using DDL statements we can able to create the architecture of the
required database.
• Below I list out types of database commands that are used in DDL. By
using those queries we can able to perform the DDL on the Database.
Create: It is used to create objects in the database
Alter: It is used to change or alter the structure of the database
objects
Drop: It is used to delete objects from the database
Truncate: It is used to remove all records from a table
Rename: It is used to rename the object in the database
Comment: It is used for comments on the data dictionary.
DCL (Data Control Language)
• The DCL stands for Data Control Language means these commands
are used to retrieve the saved data from the database. And one more
thing is the DCL execution is Transactional which means It has rollback
parameters. we have two tasks under the Data Control Language
below I listed them
Grant: It is used to give user access to the database
Revoke: It is used to take back access or permissions from the user
DML (Data Manipulation Language)
• The Data Manipulation Language is used to Manipulate the data in the database
by using different commands. In this category we can able to perform Insert new
data into Table, Update existing data in the Table, Delete Data from the Table, and
other functions we can perform on data by using these DML commands. Below I
listed those commands for your reference
Select: It is used to select data from the Table based on the requirements
Insert: It is used for Inserting data into an existing table
Update: It is used to update data in the Table based on the requirement
Delete: It is used to delete data from the Table
Merge: It is used for upsert operations
Call: It is used to call a structured query language or Java sub-program
Lock Table: It can control the concurrency
• The End.!!
