LO- 4

                                       DATABASE

                      This topic was all about types of database, database management system and database models . Let me introduce about database first. Database is an organized collection of data. The data is typically organized to model relevant aspects of reality(for e.g, the availability of rooms in hotels), in a way that supports process requiring this information (for e.g, finding a hotel with vacancies). Here are components of database:

• Data item
• Relationships
• Constraints
• Schema

Database Management System
                   It has 5 primary functions:

1. Define, create and organize a data
2. Input data
3. Process data
4. Maintain data integrity and security
5. Query database

         Examples of DBMS are Microsoft Access, SQL server and FileMaker.

There are 3 types of Database Language

1. DDL(Data Definition Language)
2. DML(Data Manipulation Language)
3. DCL(Data Control Language)

                                     DDL 

 DML

 DCL

The basic block for data models are:

• Entity
• Attributes
• Relationship

Entity- represents a particular object in the real world( a person, a place or an event). For e.g, student information system : subject, student, course, time table. 

Attributes- it is the charactristics of entity that represent by column in table.

Relationship- it describes the relationship among entities. It can be describe in a form of diagram, called ERD( Entity Relationship Diagram). There are 3 forms of ERD: 

1. One to One(1:1)  
2. One to Many(1:M)   
3. Many to Many(M:M)