1. UNIT-I Introduction to Database Management Systems
Arvind Selwal
Assistant Professor,
Department of Computer Science & IT
Arvind Selwal, Central University of Jammu

2. Arvind Selwal, Central University of Jammu
WHAT IS DBMS?
DATA: Raw facts about any thing e.g. Organization, objects, employees, customers etc.
DATABASE: A collection of two kinds of data in a container
(e.g. Storage disk)
Row data
Meta data( Data about data)
DATABASE MANAGEMENT: Creation, insertion, updation, deletion and retrieval of data in a database
DATABASE MANAGEMENT SYSTEM: A collection of data together with a set of programs for management of data in a database.
Arvind Selwal, Central University of Jammu

3. Arvind Selwal, Central University of Jammu
DBMS (cont’d)
Arvind Selwal, Central University of Jammu

4. DBMS vs FILE PROCESSING SYSTEMS
DBMS are preferred over file systems because of following merits
Data Redundancies are minimized
Inconsistencies can be reduced
Easy to access data
Data isolation problem may be resolved.
Standards can be enforced
Security can be improved.
Integrity can be improved.
Concurrent access of data possible.
Atomicity problems in file system
Arvind Selwal, Central University of Jammu

5. Arvind Selwal, Central University of Jammu
VIEWS OF DATABASE
Arvind Selwal, Central University of Jammu

6. VIEWS OF DATABASE (cont’d)
INTERNAL/PHYSICAL LEVEL
Describes how the data are stored in the database, and what relationships exist among those data.
CONCEPTUAL/LOGICAL LEVEL
Used by database administrators.
Decide what information is to be kept in the database.
One conceptual view represents the entire database.
EXTERNAL/VIEW LEVEL
Highest level of abstraction.
Only those parts of the entire database are included which are of concern to a user.
Arvind Selwal, Central University of Jammu

7. Arvind Selwal, Central University of Jammu
Database Schema
INSTANCE
The collection of information stored in the database at a particular moment is instance of a database.
SCHEMA
The overall design of the database is called the database schema.
Arvind Selwal, Central University of Jammu

8. Arvind Selwal, Central University of Jammu
DATA INDEPENDENCE
PHYSICAL DATA INDEPENDENCE
The ability to modify the physical schema without causing application programs to be rewritten.
Modifications at physical level are necessary to improve performance.
2. LOGICAL DATA INDEPENDENCE
The ability to modify the logical schema without causing application programs to be rewritten.
very difficult to achieve logical independence
Arvind Selwal, Central University of Jammu

9. Arvind Selwal, Central University of Jammu
DATABASE LANGUAGES
DDL
DML
DCL
Procedural DML
Non-Procedural DML
Database Languages
Arvind Selwal, Central University of Jammu

10. Arvind Selwal, Central University of Jammu
DATABASE LANGUAGES
1. Data-Definition Language
A database schema is specified by a set of definitions
Result of compilation of DDL statements is a set of tables that is stored in a special file called data dictionary
2. Data-Manipulation Language
By data manipulation, we mean
·        The retrieval of information stored in the database.
·        The insertion of new information into the database.
·        The deletion of information from the database.
·        The modification of information stored in the database.
A language that enables users to access or manipulate data as organized by the appropriate data mode
a. Procedural DMLs:
Require a user to specify what data are needed and how to get those data.
b.Nonprocedural DMLs
Require a user to specify what data are needed without specifying how to get those data.
3. Data Control Language
Used to ensure security, recovery, integrity and periodical backup of database.
Keeps unauthorized users away from database.
Arvind Selwal, Central University of Jammu

11. THREE LEVELS ARCHITECTURE OF DBMS
Arvind Selwal, Central University of Jammu

12. Arvind Selwal, Central University of Jammu
DATABASE USERS
Naive Users
Application
Programmers
Sophisticated
Users
DATABASE USERS
Specialized
DBA
Arvind Selwal, Central University of Jammu

13. Arvind Selwal, Central University of Jammu
DBA
A person (or a group of persons) centrally located, with an overall view of the database
Is needed to keep the database running smoothly
Such a person is called the Database Administrator (DBA)
Arvind Selwal, Central University of Jammu

14. RESPONSIBILITIES OF DBA
Arvind Selwal, Central University of Jammu

15. Arvind Selwal, Central University of Jammu
DATA BASE MODELS
A collection of conceptual tools for describing following
Data
Data relationships
Data semantics &
Consistency constraints
Arvind Selwal, Central University of Jammu

16. Arvind Selwal, Central University of Jammu
DATA BASE MODELS
DATA MODEL TYPES
Object -based Logical Models
Record -Based Logical Model
Physical Data Models
E-R Models
Object oriented Model
The Binary Model
Semantic Model
Info logical model
Functional Model
Relational model
Network Model
Hierarchical Model
Unifying Model
Frame Memory
Arvind Selwal, Central University of Jammu

17. Arvind Selwal, Central University of Jammu
HIERARCHICAL MODEL
Organizes data in a TREE STRUCTURE—consists of a collection of records connected to each other through links/pointers.
A hierarchy of parent and child data segments
Model uses Parent Child Relationships
parent to child relationship---1:N
child to parent relationship---1:1
Example: IBM's Information Management System (IMS) DBMS
A node has a single parent, but can have as many children as can have.
Arvind Selwal, Central University of Jammu

18. HIERARCHICAL MODEL (cont’d)
FID: F_NAME: DEPTT: DESIGNATION
COURSE#: ROOM
STUID: STUMANE: MAJOR: GRADE
FACULTY
CLASS
STUDENT
DEMERITS
Difficult to access values at lower levels
Model is not flexible to accommodate the dynamic needs of organizations.
Extra space required for storage of pointers.
Difficulty in insertion, deletion and updation.
Complex structure.
Arvind Selwal, Central University of Jammu

19. Arvind Selwal, Central University of Jammu
NETWORK MODEL
Extension of Hierarchical model
Like a tree except that the dependent nodes can many parents.
Uses plex structure as its basic data structure.
Network is a directed graph consisting of nodes connected by links.
Network model permits the modeling of many-to-many relationships among records/nodes.
Basic data modeling construct in the network model is the set construct.
Set consists of an owner record type, a set name, and a member record type.
Example: Conference on Data Systems Languages (CODASYL) formally defined the network model in 1971
CODASYL network model is based on mathematical set theory
SUPPLIERS A
SUPPLIERS B
PART 1
PART 2
PART 3
Arvind Selwal, Central University of Jammu

20. NETWORK MODEL-MERITS & DEMERITS
Easy to access data.
Flexible.
Efficient.
Can be applied to real world applications.
DEMERITS
Complex to design & develop.
Relationship among all the data structures is needed; need major programming efforts for changes.
Extra memory is needed for the storage of pointers.
Expensive & time for larger organization.
Arvind Selwal, Central University of Jammu