introduction-to-dbms-unit-1.ppt

Course Objectives
• To understand purpose of database
management system
• Apply concepts like database design and
database languages in managing data
• Importance of normalization in dbms and SQL
in implementation of database access
• Knowledge of transaction control , recovery
strategies , storage and indexing etc

Text Book
1.Database Management Systems,
Raghurama Krishnan, Johannes Gehrke (2007),
3rd Edition,
Tata McGraw-Hill, New Delhi, India
2.Database System Concepts
Abraham Silberschatz, Henry F. Korth, S. Sudarshan (2010),
6th Edition,
McGraw-Hill, New Delhi, India.

Roles
• Data Engineer
• Data Scientist etc

History of database systems
• Integrated Data Store, First general purpose DBMS by charles bachman at General
Electric.[Network Model]
• IBM’s Information Management System(IMS)[hierachial data model]
• SABRE system for making airline reservations By American airlines and IBM
• In 1970,at IBM’s San Jose Research laboratory proposed relational data model
• In 1980’s, SQL for relational databases by IBM
• Database transaction management james gray 1999
• IBM’s DB2, Oracle 8, Informix UDS
• ERP and MRP
• DBMS with internet
• Multimedia databases, streaming data, digital libraries ,NASA’s earth observation
system project
• Decision making and mining data repositories

Introduction to database management
systems
• Data: Data represents known facts or raw information in unorganized form
(such as alphabets or numbers or symbols ) .
• Database: Database is a organized collection of data describing the
activities of one or more related organizations.
• Database management system(DBMS) is a software designed to assist in
storing, maintaining and utilizing large collections of data.
or
A database-management system (DBMS) is a computer-software
application which interacts with end-users, other applications, and the
database itself to access,update,manage and analyze data with the help of
set of application programs.

Advantages of Database management
systems
• Data Independence
• Efficient data access
• Data integrity and security
• Data administration
• Concurrent access and crash recovery
• Reduced application development time

Database systems Vs file systems
• File storage refers to a collection of operating
system files.
• DBMS features to manage the data in a robust
and efficient manner.

Advantages of dbms over file system
• No redundant data – Redundancy removed by
data normalization
• Data Consistency and Integrity – data
normalization takes care of it too
• Secure – Each user has a different set of access
• Privacy – Limited access
• Easy access to data
• Easy recovery
• Flexible

View of data
• Abstraction
• Data Abstraction
• Instance and schema

• Abstraction :Hiding unnecessary details from the user and providing
abstract view of data which is required to users.
• Data Abstraction: Database systems are made-up of complex data
structures. To ease the user interaction with database, the developers
hide internal irrelevant details from users. This process of hiding irrelevant
details from user is called data abstraction.

Schema
• Design of a database is called schema.
• 3 types:
– Physical schema
– Logical schema
– View schema

Data models
• Data models determines the logical structure
of a database
• A Data Model is a logical structure of
Database. It describes the design of database
to reflect entities, attributes, relationship
among data, constrains etc.

Data models
• Relational data model
• Entity – relationship model
• Hierarchical data model
• Network model
• Object oriented model
• Object relational model
• Semi structured data model
• Flat data model

Hierarchical data model
• A hierarchical database model is a data model
in which the data is organized into a tree-like
structure. The data is stored as records which
are connected to one another through links.
• A record is a collection of fields, with each
field containing only one value.

Example for hierarchical model

Network model
• In the network model, entities are organized
in a graph, in which some entities can be
accessed through several paths.

Object oriented data model
• This data model is another method of
representing real world objects.
• It considers each object in the world as
objects and isolates it from each other.
• It groups its related functionalities together
and allows inheriting its functionality to other
related sub-groups.

Object relational data model
• An object-relational database (ORD), or object-relational database
management system (ORDBMS), is a database management system
(DBMS) similar to a relational database, but with an object-oriented
database model: objects, classes and inheritance are directly supported in
database schemas and in the query language

Semi structured data model:
The semi-structured data model is designed as an evolution of the relational
data model that allows the representation of data with a flexible structure.
Semi-structured data model is model where schema is part of data

• Select
– Unique
– Distinct
– Count
– As
– In
– Sum
– IS NULL
– IS NOT NULL
– ORDER BY
– AND, OR

Database users and administration
• Database users
1. Application Programmers
2. Sophisticated users
3. Specialized users
4. Stand-alone users
5. Native Users

Database administrators
• Responsibilities of DBA:
– Installing and upgrading DBMS servers
– Design and implementation of databases
– Schema definition , storage structure, access method
definition
– Performance Tuning
– Migrate database servers
– Backup and recovery
– Security
– Documentation etc

Types of database administrators
• Administrative DBA
• Development DBA
• Database Architect
• Data warehouse DBA
• Application DBA
• OLAP DBA

Transaction management
• Transaction
• Partial transactions
• Concurrent execution of transactions
• Locking protocol
• Locks
• Shared locks
• Exclusive locks
• Incomplete transactions
• System crashes
• Log
• Write Ahead Log (WAL)
• Checkpoint
• Periodic checkpoints

Introduction to database design
Database design process steps
• Requirement Analysis
• Conceptual database design
• Logical database design
• Schema refinement
• Physical database design
• Application and security design

E -R diagrams
• The E-R data model allows us to describe the
data involved in a real-world enterprise in
terms of objects and their relationships and is
widely used to develop an initial database
design.

entities
• An entity is an object in the real world that is
distinguishable from other objects.
• An Entity can be any object, place, person or
class.
• an entity is represented using rectangles.
Employee Department
Works
for

Weak entity
Weak entity is an entity that depends on
another entity. Weak entity doesn't have key
attribute of their own. Double rectangle
represents weak entity.

attributes
• An Attribute describes a property or
characteristic of an entity. For example, Name,
Age, Address etc can be attributes of a
Student. An attribute is represented using
eclipse

Types of attributes
• Key attribute
• Composite attributes
• Derived attributes

relationships
• A Relationship describes relations between
entities. Relationship is represented using
diamonds
• Relationship is an association among 2 or more
entities
• There are three types of relationship that exist
between Entities.
• Binary Relationship
• Recursive Relationship
• Ternary Relationship

relationship sets
• Collection of set of similar relationships is
called a relationship set.

additional features of the E
-R model
• Key constraints
• Key constraints for ternary relationships
• Participation constraints(partial and complete)
• Class hierarchies
• Aggregation

conceptual design with the
E-R model
• Entity versus attribute
• Entity versus relationship
• Binary versus ternary relationships
• Aggregation versus ternary relationships

conceptual design for large enterprises

• A college contains many departments
• Each department can offer any number of courses
• Many instructors can work in a department
• An instructor can work only in one department
• For each department there is a Head
• An instructor can be head of only one department
• Each instructor can take any number of courses
• A course can be taken by only one instructor
• A student can enroll for any number of courses
• Each course can have any number of students

• Step 1 : Identify the Entities
• Stem 2 : Identify the relationships
• Step 3: Identify the key attributes
• Step 4: Identify other relevant attributes
• Step 5: Draw complete ER diagram

• Step 1 : Identify the Entities
What are the entities here?
From the statements given, the entities are
• Department
• Course
• Instructor
• Student

Stem 2 : Identify the relationships
• One department offers many courses. But one particular course can
be offered by only one department. hence the cardinality between
department and course is One to Many (1:N)
• One department has multiple instructors . But instructor belongs to
only one department. Hence the cardinality between department
and instructor is One to Many (1:N)
• One department has only one head and one head can be the head
of only one department. Hence the cardinality is one to one. (1:1)
• One course can be enrolled by many students and one student can
enroll for many courses. Hence the cardinality between course and
student is Many to Many (M:N)
• One course is taught by only one instructor. But one instructor
teaches many courses. Hence the cardinality between course and
instructor is Many to One (N :1)

• Step 3: Identify the key attributes
• "Departmen_Name" can identify a department
uniquely. Hence Department_Name is the key
attribute for the Entity "Department".
• Course_ID is the key attribute for "Course" Entity.
• Student_ID is the key attribute for "Student"
Entity.
• Instructor_ID is the key attribute for "Instructor"
Entity.

• Step 4: Identify other relevant attributes
• For the department entity, other attributes
are location
• For course entity, other attributes are
course_name,duration
• For instructor entity, other attributes are
first_name, last_name, phone
• For student entity, first_name, last_name,
phone

• A typical example could be entities Customer,
Order, and Product.
• An instance of the Customer entity is
identified by a unique customer number,
• an instance of the Order entity is identified by
a unique order number, and
• an instance of the Product entity is identified
by a unique product number.

introduction-to-dbms-unit-1.ppt

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