Introduction to DBMS
- This lecture is overview of the course Database Management System
- Suppose, you want to access some website like "http://www.techtud.com/" then you make a request through the browser , this request goes to server which has got business logic but no data , so it further requests database server , which responds back by sending data to server , which ultimately responds to user by providing him a webpage.
- Following topics will be covered in upcoming videos:
- ER Model
- Relational Database Model
- Database Design
- Transaction Management
- Concurrency Control
- File Structure
- Index Structure for file
- In this video we will be discussing about DB (Database) and DBMS (Database Management System).
- DB is a collection of related data.
- Data are facts that can be recorded , ex. age of person.
- Data should have implicit meaning.
- Data should be related.
Properties of DB:
- logically coherent collection.
- some aspects of real world, mini world, representation of real purpose problems.
- data could range in size from few KBs toTBs and complexity.
What is DBMS?
- DBMS is a software collection of programs that enables user to create and manage database.
- DBMS System =Database + DBMS s/w
- This lecture explains the concept of Data Model.
- Data Model basically tells about structure, introduces you to abstraction and tells how data is stored and processed in the system.
- 3 types of Data Model exists:
- Hierarchical Model
- Network Model
- Relational Model
- it was first proposed by IBM.
- it is a tree like structure, one parent may have multiple child but child will have only one parent.
- one to many relationship exists.
- it is a graph like structure.
- child may have multiple parents.
- m:n relationship exists.
- Data is organised in form of 2D tables.
- Ex. : MySQL, Oracle,..
- Relationship among table exists.
- This lecture describes the idea of Schema, Instance, and Metadata.
- It is basically description of database.
- It is specified during database design and is expected not to be changed frequently.
Instance: It is snapshot of Database at a particular point of time, also known as current set of occurence.
Metadata: It is basically data about data.It has complete description of data.
- In this lecture the concept of Data Independence has been explained.
- Data Independence: Capacity of changing some part of schema without affecting entire schema either by deleting old database or creating new database.
- 3 levels of schema are:
- Application Schema: application programs run at this level
- Logical/Conceptual Schema: relationship exists
- Physical Schema: Storage level
- Logical Data Independence: Capacity of changing conceptual level /logic without affecting application program
- Physical Data Independence: Capacity of changing physical schema without affecting logical schema.
- This lecture discusses the roles of different Database Users.
- Different types of database users are:
- Naive user: Uses interactive GUI to do work .Ex: filling up form
- Application programmer: Writes application programs.
- Sophisticated user: can make query directly through the query processor
- Specialised User: develops knowledge based system, computer aided design, expert system
- Administrative User: he has all the permissions, can create and modify schema, can define access method, can grant permission to other users, can do routine maintenance like clearing of logs,....
- This quiz contains 5 questions on the topic Introduction to DBMS
- Learn well before you attempt the quiz
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