FLOW CHART

Databases and SQL

What is a Database?

A database is an organized collection of data that is stored in a structured way so that it can be easily accessed, managed, and updated.

The term database is made up of two words:

• Data — Raw facts and figures
• Base — A place where data is stored

Key Points About Databases

• An organized collection of data is known as a database.
• A database serves as a base from which required information can be retrieved.
• Data can be reorganized or processed to generate meaningful information.
• A database is created and managed using a Database Management System (DBMS).
• A DBMS manages a collection of databases or database files in an automated manner.

Nowadays, organizations understand the importance of proper data storage and management because accurate and timely information supports effective decision-making, which is essential for success.

What is DBMS (Database Management System)?

DBMS stands for Database Management System.

A Database Management System is software used to store, manage, and retrieve data efficiently.

It can be referred to as a digital filing system.

Definition of DBMS

A DBMS is a computerized record-keeping system designed to:

• Store data
• Modify data
• Maintain databases
• Retrieve useful information when required

It is software that gathers, processes, and manages information in an organized manner.

Functions of DBMS

A DBMS helps perform various database operations such as:

1. Adding new records
2. Editing existing records
3. Removing unwanted data
4. Sorting data in ascending or descending order
5. Extracting data using queries
6. Updating and modifying data
7. Viewing data and generating reports
8. Performing calculations

A DBMS acts as an intermediary between the user and the database.

Applications of DBMS

DBMS is widely used in many sectors, including:

• Banks
• Corporate organizations
• Railways
• Airlines
• Universities
• Hospitals
• Space research organizations

Examples of DBMS Software

Some commonly used DBMS packages include:

• MySQL
• Oracle Database
• Microsoft Access
• Sybase
• dBase
• FoxPro
• OpenOffice Base

Database Administrator (DBA)

The person responsible for managing and controlling the database system is called a Database Administrator (DBA).

A Database Administrator is an IT professional responsible for:

• Managing database operations
• Maintaining database performance
• Ensuring data security
• Managing backups and recovery

Benefits of Database Management System (DBMS)

A DBMS provides several advantages over traditional file-based systems.

1. Reduction of Data Redundancy

Data redundancy means duplication or repetition of data.

In non-database systems:

• Each application stores separate files
• This causes repeated storage of the same data
• Storage space and time are wasted

In DBMS:

• Data is stored centrally
• Duplication is minimized
• Storage efficiency improves

2. Reduction in Data Inconsistency

Data inconsistency occurs when the same data has different values in different locations.

DBMS ensures:

• Data remains consistent
• Updates are automatically applied wherever the data exists

This process is known as propagating updates.

3. Sharing of Data

DBMS allows:

• Data to be stored in one location
• Multiple users to access the same data
• Different applications to use the same data

This reduces duplication and saves time.

4. Enforcement of Data Standards

DBMS ensures that data is stored in a standardized format.

Standards may include:

• Naming conventions
• Data formats
• Report structures
• Table structures

5. Data Security

DBMS ensures that:

• Only authorized users can access data
• Different users have different permission levels
• Sensitive data remains protected

6. Data Integrity

Data integrity means maintaining the accuracy and validity of data.

DBMS ensures:

• Only valid data is stored
• Rules are followed while entering data

7. Interactive Interface

DBMS provides a user-friendly interface that allows users to:

• Enter data easily
• View stored data
• Search required information quickly

In traditional systems, data was poorly organized, making it difficult to find information. DBMS solves this problem.

Elements of a Database

A database contains several important components.

Table

A table is a collection of logically related records.

• Data is stored in rows and columns
• Multiple records are arranged together in tabular form
• Columns represent fields
• Rows represent records

Example:

Field

A field represents a single column in a table.

• It contains a specific type of data
• It represents one attribute of a record
• It is a vertical column in a table

Example:

• Name
• Age
• Address

Record

A record is a collection of related data stored in fields.

• It represents a single row in a table
• It contains complete information about one item

Example:

This row is called a record.

Components of a Database Package

A database package typically includes the following components:

1. Tables
2. Queries
3. Forms
4. Reports

1. Tables

A table is the basic storage unit of a database.

• Stores data in rows and columns
• Acts as a container for records

2. Queries

A query is a request used to retrieve specific data from tables.

Queries help to:

• Filter large volumes of data
• Display required information
• Retrieve records from one or more tables
• Produce results based on specific conditions

3. Forms

A form is a layout that provides an interface to:

• Enter new data
• Modify existing data
• View stored records

Forms make data entry simple and user-friendly.

4. Reports

A report displays data in a structured format based on user requirements.

Reports are used to:

• View information
• Print data
• Present formatted results
• Combine data from one or multiple tables

Reports can be previewed on screen or printed on paper.

Field Name

A field name is the identifier used to represent a field in a table.

It describes the type of data stored in that field.

Example:

• Name — Stores student names
• Age — Stores student ages

Rules for Field Names

• Can contain letters and numbers
• Can include special characters such as:
  • Period (.)
  • Exclamation mark (!)
  • Square brackets [ ]
• If the field name contains multiple words, use an underscore (_) between words.

Example:

Student_Name

Date_Of_Birth

Field Type (Data Type)

A field type defines the type of data that can be stored in a field.

It determines:

• What kind of data can be stored
• What operations can be performed on the data

Example:

If a field Marks stores numbers only, its data type should be Numeric.

The data type of a field depends on the values that will be stored in that field.

Field Properties

Field properties control the behavior of fields in a database.

They help maintain data consistency and accuracy.

Common Field Properties

Entry Required

This property ensures that:

• The field cannot be left blank
• The user must enter a value

Auto Value (Auto Increment)

This property automatically generates values for a field.

Example:

• Student ID
• Order Number

Users cannot manually enter values in this field.

Length

This property specifies the maximum length of data allowed in a field.

Examples:

• Numeric fields — length depends on numeric type
• Text (VARCHAR) — default length may be 50 characters
• Boolean (Yes/No) — typically stores True or False

Default Value

This property automatically inserts a default value when no value is entered.

Example:

Default Status = "Active"

Format

This property determines how data is displayed.

Examples:

• Date format (DD/MM/YYYY)
• Currency format
• Number format