Introduction to databases

Subject: Computer Basics

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Overview

Database is a collection of data organized to service many applications at the same time by storing and managing data so they appear to be at one location. This note provides an information on database.
Introduction to databases

What is database?

Database is a collection of data organized to service many applications at the same time by storing and managing data so they appear to be at one location.

Definition of some terms used in database

Data: Data are the facts or figures obtained from various sources.

Information: Information is the processed data.

Table: A database object comprising of related data entries is known as a table. Data present in a table is displayed in the form of rows and columns.

Field: A field is a piece of information about an element which may be a person, student or employee.

Record: A collection of related field is called record.

Cell: A cell is an intersection of rows and columns.

Data redundancy: Data redundancy means the repetition of data in a database.

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Relational Database: A Database Management System that stores data in the form of related tables is known as a relational database.

Database model: A database model is the manner in which the data collection is stored, managed and administered.

Relationship: It is a link or association between several entries. Following is the list of different types of relationship

  • One to one e.g: Driver and car
  • One to many e.g: Teacher and students
  • Many to many e.g: Books and readers
  • Many to one e.g: Students and school

Primary key

A primary key is the field that uniquely identifies in a table. Each record in the table must be unique. Every table has only one primary key. There are two types of primary keys as follows.

  • Compound (Composite key): A compound key is a key that consists of multiple columns because one column is not sufficient.
  • Foreign key: A foreign key is the linking pin between two tables.

Data Type

A data type specifies the type of data that a field can hold. It is a form of storage which allows entry of previously defined values that each field can store. Some example of data types are as follows:

  • Text Data Type
  • Numeric Data Type
  • Date Data Type

Objectives of Database

  • Elimination of data redundancy.
  • Share data among all users.
  • Incorporate changes easily and quickly.
  • Simplify the use of data files.
  • Lower the cost of storing and retrieving data
  • Improve accuracy and consistency.
  • Provide data security from unauthorized access and use
  • Exercise center control over standards.
  • Get persist-ency in data.
Things to remember
  • Database is a collection of data organized to service many applications at the same time by storing and managing data so they appear to be at one location.
  • A database object comprising of related data entries is known as a table.
  • A Database Management System that stores data in the form of related tables is known as a relational database.
  • A database model is the manner in which the data collection is stored, managed and administered.
  • It includes every relationship which established among the people.
  • There can be more than one community in a society. Community smaller than society.
  • It is a network of social relationships which cannot see or touched.
  • common interests and common objectives are not necessary for society.
Videos for Introduction to databases
2 - What is a Database
MySQL Database Tutorial - 1 - Introduction to Databases
Questions and Answers

Database is a collection of data organized to service many applications at the same time by storing and managing data so they appear to be at one location.

list of different types of relationship are:

  • One to one e.g: Driver and car
  • One to many e.g: Teacher and students
  • Many to many e.g: Books and readers
  • Many to one e.g: Students and school

The objectives of database are:

  • Elimination of data redundancy.
  • Share data among all users.
  • Incorporate changes easily and quickly.
  • Simplify the use of data files.
  • Lower the cost of storing and retrieving data
  • Improve accuracy and consistency.
  • Provide data security from unauthorized access and use
  • Exercise center control over standards.
  • Get persist-ency in data.

Some example of data types are as follows:

  • Text Data Type
  • Numeric Data Type
  • Date Data Type

A relational database management system is defined as the database management system that stores data in the form of related tables.

A primary key is a special relational database table column (or combination of columns) designated to uniquely identify all table records.

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