DB for orientation presentationsand.pptx

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1. DATABASE SYSTEM CONCEPTS R.Sridevi, Assistant Professor of Computer Science, Bharathidasan Govt. College for Women, Puducherry- 605 003.

2. Data vs. Information What is the difference? What is data? Freshly collected facts. Unprocessed information. What is information? Processed data Data is converted into information, and information is converted into knowledge. Data Information Knowledge Action

3. What is a database? A database is any organized collection of data stored with minimum redundancy. Some examples of databases you may encounter in your daily life are: A telephone book Student information system Airline reservation system

4. Why do we need a database? Keep records of our: Customers Employees Keep a record of activities Develop reports

5. DataBase Management System (DBMS) Collection of interrelated data & set programs used to access this data. Provides a convenient environment to retrieve & store database information Database System consists of two parts DB Mgmt System DB Application

6. Advantages of DBMS Redundancy can be reduced Inconsistency can be avoided Data can be shared Security restrictions can be applied Integrity can be maintained

7. Data Models Entity-Relationship (E-R) model Relational Database model

8. Basic terms in E-R Model Entity is any object, place, person, concept or activity. Attribute is the Characteristics property of an entity. Relationship is an association among entities.

9. Symbols used in E-R Model Entity is denoted by Attribute is denoted by Relationship is denoted by

10. Relationship Types One-to-one One-to-many Many-to-many Student 1 Roll No.1 Assigned Student 1 Course Registe r Student 2 Supplier 1 Supplier 2 Item 1 Item 2

11. Example of E-R Model

12. Relational Database Model Dr. E.F Codd first introduced this model in 1970. Allows data to be represented in a simple row-column format (i.e.) table . Each data field is considered as a Column . Each record is considered as a row of a table.

13. Example of Relational model customer- name Customer- Id customer- street customer- city account- number Johnson Smith Johnson Jones 192-83-7465 019-28-3746 192-83-7465 321-12-3123 Alma North Alma Main Palo Alto Rye Palo Alto Harrison A-101 A-215 A-201 A-217 a Field (Column) a Record (Row)

14. Advantages of Relational Model Adding & deleting a record to/from the existing table is easy. Adding & deleting a Field to /from the existing table is easy. It is not necessary to build the entire database from scratch.

15. Examples of RDBMS Packages Sybase Oracle SQL Server