Introduction to SQL

SQL stands for Structured Query Language. It is the standard language used to communicate with relational databases. SQL allows us to store data, retrieve data, update records, and manage large datasets efficiently.

What is a Database?

A database is an organized collection of data stored electronically. Instead of storing information in files or spreadsheets, databases store data in structured tables, making it faster, safer, and easier to manage.

Examples of things stored in databases:

• User information (name, email, password)
• Product details (price, category, stock)
• Employee records
• Transaction history

What is SQL Used For?

SQL is used to interact with relational databases. With SQL, you can:

• Create databases and tables
• Insert new data
• Read and filter data
• Update existing records
• Delete unwanted data
• Control access and security

Popular Databases That Use SQL

SQL is supported by almost all relational database systems, including:

• MySQL
• PostgreSQL
• SQL Server
• Oracle Database
• SQLite

Your First SQL Query

Let’s look at a very simple SQL query. This query selects all records from a table called employees.

SELECT * FROM employees;

Explanation:

• SELECT tells the database what data we want
• * means “all columns”
• FROM employees specifies the table name

Why Learn SQL?

SQL is one of the most important skills in data, software, and business roles. It is used by:

• Data Analysts
• Data Scientists
• Backend Developers
• Business Analysts
• Database Administrators

SQL is easy to learn, powerful, and works the same way across different database systems.

What You Will Learn in This Course

In this SQL course, you will learn:

• How to write basic and advanced SQL queries
• How to filter and aggregate data
• How to work with multiple tables using joins
• How to optimize queries for performance
• How to design real-world database systems

By the end of this course, you will be able to confidently work with databases using SQL.