1. Getting started
with DBMS
Prepared By:
Prerana Bhattarai

2. • Introduction to Database Management System
• DBMS vs File System
• View of data
• Data models
• Database Languages: DML, DDL
• Database users and administrators
• Transaction Management
• Database System Structure
• Application architectures
The slides include:

3. • A DBMS is a collection of software programs that allows
a user to define data types, structures, constraints, store
data permanently, modify and delete the operations.
• DBMS is basically a software used to add, modify, delete,
select data from the database.
• In simpler words, DBMS is a collection of interrelated
data and software programs to access those data.
Introduction to Database
Management System

4. Bases DBMS Flat file system
Definition
Data
redundancy
Cost
Use
Views
DBMS is a collection of interrelated data
and software programs to access those
data.
There is no problem of data redundancy.
DBMS software are very costly and also
regular update makes it costly.
Mostly, large organizations use DBMS
who can afford it and have a large
number of client and employees to be
managed.
Views are created and an employees
can’t see all information available, hence
there is security.
Flat file system stores data in a plain
text file. Here, the records are specified
in a single line.
There is main problem of data
redundancy.
Flat file are cost effective.
Small organizations use it as it is cost
effective and who have to deal with
small number of clients and
employees.
Any information can be seen by
anyone, hence there is no security.
DBMS VS Flat file system

5. View 1 View 2 View N
Logical level
Physical level
Views of data
View level
Conceptual
level
Internal
level
Stored
database

6. • It is a process of easy user interface to users by hiding
underlying complexities of data management from users.
• It defines views; which user can view which part.
• Database system provides users with abstract view of the
data.
• It only shows a part of database that a user needs.
Data abstraction

7. • It is the lowest level of abstractions and describes how
the data are stored on the storage disk and access
mechanisms to retrieve the data.
• DBMS developer is concerned with this level.
• This level emphasis on minimizing the number of disks
access so that data can be retrieved very fast.
• It describes complex low-level data structures in detail.
Physical Level

8. • This level describes what data are stored in the database
and the relationships between the data.
• It describes stored data in terms of the data model.
• It describes the database in terms of small number of
relatively simple structures.
Logical Level

9. • Every user don’t need to access all information stored in
the database.
• This level is basically concerned with dividing the
database according to the need of the database users.
• It simplifies the interaction of the users with the system.
View Level

10. • The basic design or the structure of the database is the
data model.
• It is a collection of conceptual tools for describing data,
data relationships, data semantics, and consistency
constraints.
• The basic structure of the database that organizes data,
defines how the data are stored and accessed, and the
relationships between the data, is the data model.
Data Model

11. • Hierarchical Model
• Network Model
• Entity-Relationship(E-R) Model
• Relational Model
• Object-Oriented Model
• Object-Relational Model
Types of database
models

12. • Data is represented as a tree.
• A record type can belong to only one owner type but a
owner type can belong to many record type.
Hierarchical Data Model

13. • It is modified version of Hierarchical Data Model where
it allows more general connections among the nodes as
well.
• They are difficult to use but are more flexible than
hierarchical databases.
Network Data Model

14. • It is a lower level model that uses a collection of tables to
represent both data and relationships among those data.
• Each table has multiple columns, depending on the
number of attributes, and each column has a unique
name.
Student
sid sname Standard
A-101 Ramesh 11
A-102 Kriti 10
A-103 Laxmi 12
Relational Model

15. • It is a high level model based on the need of the
organization.
• Its entities are distinguishable from other objects and
relationship is an association among several entities.
Student Borrows Books
sid sname standard bid author
E-R Model

16. • It represents entity sets as class and a class represents both
attributes and the behavior of the entity.
• Instance of a class is an object.
• The internal part of the object is not externally visible.
• One object communicates with the other by sending messages.
Object-Oriented Model

17. • It combines the feature of relational data model and
object-oriented data model.
Object-Relational Model

18. • Data Definition Language(DDL):
• Database language that is used to create, delete or modify
database schema is called DDL.
• It is used by Database Administrators(DBA) to specify the
conceptual schema.
• DDL interpreter converts DDL statements into equivalent
low level statements understood by the DBMS.
• Normally, create, alter, and drop statements are DDL
statements.
• DDL statements make changes in the schema
Database Languages
(DDL, DML)

19. Example: For create command
create table Student
(
sid char(4),
sname varchar(50),
standard integer
);
DDL cont’d
Example: For drop command
drop Student;
Example: For alter command
alter table Student
ADD COLUMN address varchar(20)
;

20. • Database language that enables insert, update, delete, and
retrieval of data from the database is called Data
Manipulation Language.
• DML complier converts DML statements into equivalent
low level statements that the database understands.
• Normally, insert, update, delete, select are DML
commands.
• DML reflects change in the instance, not the schema
DML

21. Example: For insert
Insert into Student
values(“A-101”,
“Ramesh”, 12);
Example: for update
Update Student
Set class = 11
Where sid = “A-101”
; Example: For delete
DML cont’d
Example: for select
Select *
From Student
Delete from standard
Where sname = “Kriti”
Note: In SQL, cases are insensitive. So, instead of Student one can write StUdEnT as
well.
Also, for integer values “12” is incorrect but 12 is correct.
And, for char and varchar “Kriti” is correct and Kriti is incorrect.

22. • Users are distinguished by the way they interact with the
database system.
1. Naïve users:
• They interact with the system by invoking one of the
application programs written previously. Naive users are
bank teller, receptionist, etc.
• For e.g., bank teller needs to add Rs.90 to account Ram,
and deduct the same amount from account Sita. Then the
application program the bank teller uses is transfer.
Database users and
administrators

23. 2. Application programmers:
They are specializes computer professionals who write the
application programs for naïve users and for easy user interface
can use an tools.
3. Sophisticated users:
They make request to the database with writing application
programs.
4. Specialized users:
They are experts who write database application like system
storing complex data types, CAD systems that do not fit to the
traditional data-processing framework.
Database users and
administrators cont’d

24. Database administrators:
DBA is a person who has control over data and the associated
application programs. He is the one who can define schema,
install new software, enforcing security to the system, etc.
Major responsibilities of DBA are:
1. Define schema and modify as per needed
2. Install new software for efficient operations
3. Enforcing and monitoring security
4. Analyzing the data stored in the DBMS
5. Keeping the backup of the DBMS periodically
6. Ensuring the state of the hardware and software
Database users and
administrators cont’d

25. • Collection of operations that form a single logical unit of
work are called transaction.
• Transaction management ensures that the database system
have ACID properties.
A = atomicity
C = consistency
I = isolation
D = durability
Transaction Management

26. 1. Atomicity:
Atomic means whole. This property ensures that the
changes made to the database are wholly reflected or no
change is made. But partial changes or execution are not
made.
2. Consistency:
The database must move from one consistent state to
another after the execution of the transaction.
Properties of Transaction
Management (ACID property)

27. 3. Isolation:
Even if many transaction may be done at the same time but
isolation ensures that if transaction A and B are executing
concurrently, then either A must execute first then B is
executed or, B must execute first then A is executed.
4. Durability:
Changes made to the database are permanent and even if the
system failure occurs, that don’t lead to the erase of the
transaction executed previously.
Properties of Transaction
Management (ACID property) cont’d

28. Database system structure

29. 1. Storage Manager
2. Disk Storage
3. Query Processor
Its components are:

30. • Storage manager stores, retrieves, and updates data in the
database. It translates DML statements into low level
statements that the database understands
• Its components are:
• Authorization and integrity manager: It checks for the
correctness of the constraints specified and also checks the
authenticity of the users while entering the database.
• Transaction manager: It ensures that the database follows the
ACID property.
• File manager: It is responsible to manage allocation of space on
the disk storage.
• Buffer manager: It is responsible for fetching data from the disk
storage and to decide what data to cache in the main memory. It
enables to handle data sizes which are larger than the size of the
disk.
1. Storage Manager

31. • It is responsible for allocating the disk space and also for
maintaining the data in the database.
• Its components are:
• Data files: It is the place where database is stored,
• Data dictionary: It stores metadata about the schema of the
database.
• Indices: It provides quick access to the data items that hold
particular values.
2. Disk Storage

32. • It simplifies and facilitates easy access to the data.
• It translates queries written in non-procedural language,
and operates the statement.
• Its components are:
• DDL interpreter: It interprets DDL statements into low-level
language understood by the system.
• DML compiler: It translates DML statements into an
evaluation plan consisting low level instructions that the
query evaluation engine understands.
• Query evaluation engine: It executes low level statements
generated by the DML compiler.
3. Query Processor

33. • In two tier architecture, user interface and application
programs are on the client side and query and transaction
facility are on the server side
• When DBMS access is required, the application program
establishes connection with client and server
• Client queries and server provides response to the
authenticated client request/queries.
• There is direct interaction of client with the server
• The business logic coupled with either client side or the
server side.
Two-tier architecture

34. Two Tier architecture

35. ADVANTAGES DISADVANTAGES
• Suitable for
environments where
business rules do
not change
frequently
• number of users are
limited
Advantages
Disadvantages
• Useless for large
scale organizations
• Only a limited
number of clients
can access

36. • In three tier architecture, user interface and application
programs are on the client side and query and transaction
facility are on the server side and in between there is an
intermediate layer which stores business
rules(procedures/constraints) used to access data from the
database.
• When DBMS access is required, the application program
establishes connection with client and server but before
forwarding the request of client, application rules check the
client credentials.
• There is indirect interaction of client with the server but direct
connection of client and application rules and application rules
and the server.
Three Tier Architecture

37. Three Tier Architecture

38. ADVANTAGES DISADVANTAGES
• Efficiency
• Security
• Scalability
• Flexible
Advantages
Disadvantages
• More complex
structure
• More difficult to
setup and maintain
• Expensive

39. • Instance: The collection of information currently stored in
the database at the particular period.
• Schema: The overall design of the database that is not
expected to change frequently.
• Mapping:
• Metadata: Data about data.
• Data dictionary: A special file that stores metadata.
• Methods: Values and bodies of codes that the object
contains.
Common terms used in
DBMS