dbms

1. DATABASE MANAGEMENTDATABASE MANAGEMENT
SYSTEMSSYSTEMS
MJS-15
BY
Abhishek & Sai Kumar

2. Introduction to DBMS
What is Database?
Purpose of Database Systems
File System vs. DBMS
View of Data
Data Models
RDBMS
DDL
DML
DCL
TCL
MJS-15 Index

3. MJS-15 Introduction
1
• A software used to manage data.
• A very large, integrated collection of data.
• A collection of information stored in a computer in
a systematic way.
Databases
• MySql
• Postgresql
• Oracle
What is Database..?

4. Database Management System
(DMBS)
Collection of interrelated data
DMBS contains information about a particular
enterprise
DBMS provides an environment that it both
convenient and efficient to use
MJS-15 Introduction
2

5. File System vs. DBMS
advantages disadvantages
FMS • Simpler to use
• Less expensive
• Typically no multi-user access
• Limited to smaller databases
• Limited functionality
• Decentralization of data
• Redundancy and integrity issues
DBMS • Greater flexibility
• Greater processing power
• Ensures data integrity
• Supports simultaneous
access
• Provides backup and
recovery controls
• Advanced security
• Difficult to learn
• Packaged separately from the
OS
• Slower processing speeds
• Requires skilled administrators
• Expensive
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6. Purpose of Database Systems
Data redundancy and inconsistency
Difficulty in accessing data
Data isolation – multiple files and formats
Integrity problems
Concurrent access by multiple users
Security problems
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Database management systems were developed
to handle the following difficulties of typical file-
processing systems supported by conventional
operating systems:

7. View of Data
An architecture for a database system
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Physical
level
Logical
level
View
level

8. Levels of Abstraction
Physical level: describes how a record (e.g.
customer) is stored.
Logical level: describes data stored in database,
and the relationships among the data.
type customer = record
name: string;
street: string;
city: integer;
end;
View level: application programs hide details of
data types. Views can also hide information (e.g.
salary) for security purposes.
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9. Instances and Schemas
Similar to types and variables in programming languages
Schema – the logical structure of the database (e.g., set
of customers and accounts and the relationship between
them)
Instance – the actual content of the database at a
particular point in time
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10. Data Models
A collection of tools for describing:
Data relationships
Data constraints
Object-based logical models
Entity-relationship model
Record-based logical models
Relational model (e.g., SQL/DS, DB2)
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11. Entity-Relationship Model
Example of entity-relationship model
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customer accountdepositor
social-security customer-street
customer-name
account-number
balancecustomer-city

12. What is RDBMS..?
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• RDBMS stands for Relational Database
Management System.
• RDBMS data is structured in database tables,
fields and records.
• In this data will be stored in the from rows and
columns.
• RDBMS also provide relational operators to
manipulate the data stored into the database
tables.

13. Relational Model
Example of tabular data in the relational model:
MJS-15 Introduction 11
name ssn street city account-number
Johnson 192-83-7465 Alma Palo Alto A-101
Smith 019-28-3746 North Rye A-215
Johnson 192-83-7465 Alma Palo Alto A-201
Jones 321-12-3123 Main Harrison A-217
Smith 019-28-3746 North Rye A-201
account-number balance
A-101 500
A-201 900
A-215 700
A-217 750

14. MJS-15 Introduction 12
There are four types of query languages as follows.
•Data Definition Language (DDL)
•Data Manipulation Language (DML)
•Data Control Language (DCL)
•Transaction Control (TCL)
RDBMS Query Languages.

15. Data Definition Language (DDL)
A DDL is a language used to define data structures and
modify data.
DDL Commands:
•Create
•CREATE TABLE employee(empID int, Ename char(20), Esalary int, Eadd varchar(25));
•Alter
•ALTER TABLE employee ADD Ecountry varchar (50);
•Drop
•DROP TABLE employee;
•Truncate
• TRUNCATE TABLE employee;
•Rename
•SELECT Ename AS Emp_name FROM employee;
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16. Data Manipulation Language
(DML)
A DML is a language used for managing data in
database.
DML Commands:
•Select
• SELECT * FROM employee;
•Insert
•INSERT INTO employee(EmpId, Ename, Esalary, Ecity)
VALUES (502 ,‘sandeep',‘25000',hyderabad' );
•Update
•UPDATE employee SET Ename=‘bharath', where Ecity=hyderabd';
•Delete
•DELETE FROM Employee WHERE Ename=‘sandeep‘;
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17. Data Control Language (DCL)
A DCL is a language used to control privilege in
Database
DCL Commands:
•Grant
•Syntax: REVOKE [permission] ON database.table FROM 'user‘@'localhost';
Example: GRANT [write] ON [company_details].[employee] TO ‘[sandeep]’@'localhost’;
•Revoke
•Syntax: REVOKE [permission ]ON database.table FROM 'user‘@'localhost';
Example: REVOKE [write] ON Company_details.Employee FROM ‘Sandeep'@'localhost';
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18. Transaction Control Language (TML)
A TCL is a language used to manage transactions in
database
TCL Commands:
•Commit : save work done
•Syntax: commit
•Rollback : restore database to original since the last COMMIT
•Syntax: rollback;
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19. Any Queries…?
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