Introduction To Databases

Introduction To Databases, What is Data?, What is Information?, Types of Data. What is Database?, Database Objects, Types of Databases, and Database Management System.

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Introduction To Databases

1. What is Data?
2.  What is Information?
3. Quantitative and Qualitative Data
4. Data Types
5. What is Database?
6. Types of Database Models
7. Types of Databases

1. What is Data?

Data can be defined as a representation of facts, concepts, or instructions in a formalized manner, which should be suitable for communication, interpretation, or processing by human or electronic machine.

Data is represented with the help of characters such as alphabets (A-Z, a-z), digits (0-9) or special characters (+,-,/,*,<,>,= etc.)

2. What is Information?

Information is data that has been processed in such a way as to be meaningful to the person who receives it. it is any thing that is communicated.

3. Quantitative and Qualitative Data

Quantitative data refers to any information that can be quantified. If it can be counted or measured, and given a numerical value, it’s quantitative data.

Quantitative data can tell us “how many,” or “how much,” or “how often,” etc.

Examples of Quantitative Data

  • height
  • weight
  • number of objects
  • volume
  • temperature
  • pressure
  • price
  • speed
  • percentages

Qualitative Data: Unlike quantitative data, qualitative data cannot be measured or counted. It’s descriptive, expressed in terms of language rather than numerical values.

Examples of Qualitative Data

  • feelings and emotions
  • texture
  • flavor
  • expressions of more/less, ugly/beautiful, fat/thin, healthy/sickly


4. Data Types

A data type is a classification of data which tells the compiler or interpreter how the programmer intends to use the data. The data type defines which operations can safely be performed to create, transform and use the variable in another computation.


1. String – Text (Examples: Hello World, G C Reddy, India123*)
2. Integer – Whole numbers (Ex: 123)
3. Float – Number with a decimal point (Ex: 123.456)
4. Character
5. Boolean – Represents logical values (Ex: true or false)

5. What is Database?

A database is an organized collection of structured information, or data, typically stored electronically in a computer system. A database is usually controlled by a database management system (DBMS).

Oracle, MS SQL Server, MySQL, MongoDB, Cassandra, Redis, etc.

Tables are database objects that contain all the data in a database. In tables, data is logically organized in a row-and-column format similar to a spreadsheet. Each row represents a unique record, and each column represents a field in the record.

In SQL databases a table is also known as a relation.

Columns / Fields
Tables contain rows and columns, where the rows are known as records and the columns are known as fields. A column is a set of data values of a particular type (like numbers or alphabets), one value for each row of the database, for example, Age, Student_ID, or Student_Name.

In a database, a record (sometimes called a row) is a group of fields within a table that are relevant to a specific entity.

6. Types of Database Models

Database models are basically known as database schemas, which are used to represent database structure and the format of database which is managed by the database management system.

Important Database Management Systems are:

  1. Hierarchical databases
  2. Network databases
  3. Object-oriented databases
  4. Relational databases
  5. Non-Relational or NoSQL databases


i. Hierarchical Databases
Just as in any hierarchy, this database follows the progression of data being categorized in ranks or levels, wherein data is categorized based on a common point of linkage.

ii. Network Databases
A network database is a hierarchical database, but with a major tweak. The child records are given the freedom to associate with multiple parent records.

iii. Object-oriented databases
An object-oriented database is a collection of object-oriented programming and relational database. There are various items which are created using object-oriented programming languages like C++, Java which can be stored in relational databases, but object-oriented databases are well-suited for those items.

iv. Relational databases
A relational database is a collection of data items with pre-defined relationships between them. These items are organized as a set of tables with columns and rows. Tables are used to hold information about the objects to be represented in the database. Each column in a table holds a certain kind of data and a field stores the actual value of an attribute. The rows in the table represent a collection of related values of one object or entity.

Some of the more popular Relational databases are Oracle, MS SQL Server, MySQL, IBM DB2, and PostgreSQL.

v. Non-relational or NoSQL databases
The non-relational database, or NoSQL database, stores data. However, unlike the relational database, there are no tables, rows, primary keys or foreign keys. Instead, the non-relational database uses a storage model optimized for specific requirements of the type of data being stored.

There are four popular non-relational types: document data store, column-oriented database, key-value store and graph database. Often combinations of these types are used for a single application.

Some of the more popular NoSQL databases are MongoDB, Apache Cassandra, Redis, Couchbase, and Apache HBase.

7. Types of Databases

Depending upon the usage requirements, there are following types of databases available in the market −

i. Centralized database.

A centralized database (CDB) is a database that is located, stored, and maintained in a single location. This location is most often a central computer or database system, for example a desktop or server CPU, or a mainframe computer.

ii. Distributed database.

A distributed database is a collection of multiple interconnected databases, which are spread physically across various locations that communicate via a computer network.

iii. Personal database.

Personal database system is the local database system which is only for one user to store and manage the data and information on their own personal system.

Personal database management system requires only one application to store and manage data in personal computer.

iv. End-user database.

An end user database is simply a software which helps store data created by an end user.

v. Commercial database.

A commercial database is one created for commercial purposes only and it’s available at a price. Unlike open source databases, commercial databases can only be viewed or modified by authorized users.

vi. NoSQL database.

NoSQL databases (aka “not only SQL”) are non-tabular databases and store data differently than relational tables. NoSQL databases come in a variety of types based on their data model. The main types are document, key-value, wide-column, and graph.

vii. Operational database.

The Operational Database is the source of information for the data warehouse. It includes detailed information used to run the day to day operations of the business. The data frequently changes as updates are made and reflect the current value of the last transactions.

Operational Database Management Systems also called as OLTP (Online Transactions Processing Databases), are used to manage dynamic data in real-time.

viii. Relational database.

A relational database is a type of database that focuses on the relation between stored data elements. It allows users to establish links between different sets of data within the database and use these links to manage and reference related data.

Many relational databases use SQL (Structured Query Language) to perform queries and maintain data.

ix. Cloud database.

A cloud database is a database that is built, deployed, and accessed in a cloud environment, such as a private, public, or hybrid cloud.

x. Object-oriented database.

An object-oriented database (OODBMS) or object database management system (ODBMS) is a database that is based on object-oriented programming (OOP). The data is represented and stored in the form of objects.

xi Graph database.

A graph database is defined as a specialized, single-purpose platform for creating and manipulating graphs. Graphs contain nodes, edges, and properties, all of which are used to represent and store data in a way that relational databases are not equipped to do.

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