Topic Four

Topic four we learnt about Apply relational database design approach and implement it using Microsoft Access or other DBMS.

First we came to know what is database?

 - An organized collection of data.

- Collection of information arranged and presented in alphabetical order.

- Mechanism for strong, managing and retrieving information.

 Functions of database  

There are several functions that a database performs to ensure data reliability and regularity of data in the database. The three functions of database is to organize, to store and to control.

similarly we learnt about components of database and fundamentals of database. There are two components of database which is data item its a field in data processing and it is a piece of information  and another one is schema describes the organization of data and relationships within the database. It consists  of definitions of the various types of record in the database, the data-items they contain and the sets into which they are grouped. 

    

Topic four we also learnt about Database Management System (DBMS). First i came to know about what is DBMS, DBMS is a software package designed to define, manipulate, retrieve and manage data in a database. A DBMS generally manipulates the data itself, the data format, field names, record structure and file structure. It also defines rules to validate and manipulate this data. For example Microsoft Access, MySQL, Oracle, File maker, dBASE are all examples of database management systems. DBMS can provide some features which are listed below:

- Allow users to create new databases.

- Give users the ability to query & modify the data using appropriate language (query language or      data manipulation).

- It provides information to the decision makers that they need to make important decisions. This    information is provided by querying the database using SQL.

And next session we learnt about data model basic building blocks. The basic building block for all data models are : 

Entity: An entity is something that we will be storing data about it is more to do with relational theory. It can be thought of as nouns and it represents in tables. 

Attributes: attributes is a characteristic of entity it help to identify the entity. It represents by col-um in table.

  

Relationship: A relationship works by matching data in key columns usually with the same name in both tables. In most cases. the relationship matches the primary key from one table, which provides a unique identifier for each row with an entry in the foreign key in the other table. There are three types of relationship between tables.

One to One Relationship: 

One to Many Relationship:

 Many to Many Relationship:

Types of Database Models

Hierarchical Model: It was established in 1960s by Information Management Company (IBM).This model organizes data in tree structure and it contains levels or segment like organizational chart. Hierarchical establish one to many relationship. 

Network Database: The popularity of the network database model coincided with the popularity of the hierarchical data model. It was created to represent complex data relationship and network database allows many to many relationships.

Relational database: It was introduced in 1970 by E. F. Codd . In relational data model, data is organised in the form of rows and columns as in a table.