Introduction to Databases and SQL

SQL Tutorials

Introduction to Databases and SQL is the initial course for anyone who is interested in learning how applications store and organize data. This course will teach you what a database is, why developers use SQL and how SQL interacts with databases in real, world systems.

What is a Database

Data is stored in a structured manner, persistently, in a database.

Imagine a database as a computer cupboard. There are no papers in it, but instead information such as names, dates and orders are stored there. The information is in a structured way so it is very quick and easy to retrieve and modify.

For example, a website database stores
user details
product lists
orders and payments

As the data becomes large, the file can be difficult to control if stored without structure, such as in Text Documents and spreadsheets. Databases provide structure to keep the data clean and ordered.

Why Databases Are Important

Databases are important because they:

store large amounts of data
help you find data quickly
Protect your information
Minimize duplication of data
allow many users to access data at the same time

Because of these advantages, almost every app or website you use relies on a database. Without databases, today’s programs would not be fast and would be very difficult to manage.

What is SQL

SQL stands for Structured Query Language.

SQL is the language we use to speak to a database. It provides us with a method for giving instructions which will be taken on board.

With SQL, we can
add new data
retrieve data from tables
update existing records
delete unwanted data

We write these instructions as SQL commands, which gives us full control over the data.

Simple Example

Imagine a table that stores user names.

If you want to see all users, SQL lets you ask the database
show me all users

Because you write this request in SQL, the database understands it and returns the correct result.

Databases That Use SQL

Many popular databases use SQL, such as
MySQL
PostgreSQL
Oracle
SQL Server
SQLite

Even though these databases differ, they all follow the same basic SQL rules. As a result, once you learn SQL, you can work with many database systems.

SQL and Tables

Databases organize data into tables.

A table appears as a grid with rows and columns. Rows are used to store records and in columns are stored the info.

For example, a users table may include
id
name
email

Each row represents one user. This clear structure helps developers keep data easy to read and manage.

Where SQL Is Used

SQL is used by people in a wide variety of applications such as:

Websites
Mobile apps
Office software
Banking systems
Online stores
Data analysis

So, regardless of whether you are a software engineer, web developer, quality analyst, research scientist, or even a data analyst or data scientist, once you learn SQL you will definitely be benefitted.