📊 Lesson 1: What is SQL?
⏱️ Estimated time: 10 minutes | Difficulty: Beginner
The Language of Data
SQL (Structured Query Language) is the standard language for dealing with Relational Databases. It is used to insert, search, update, and delete database records.
SQL = Structured Query Language
SQL is the standard language for storing, retrieving, and managing data in relational databases. It's used by virtually every application that works with data.
Where SQL is Used
- 📱 Mobile apps (SQLite)
- 🌐 Web applications (MySQL, PostgreSQL)
- 🏢 Enterprise systems (Oracle, SQL Server)
- 📊 Data analysis & reporting
- 🤖 Machine learning data pipelines
What is a Relational Database?
Data is organized in tables (like spreadsheets) with rows and columns. Tables can relate to each other.
┌──────────────── users ────────────────┐
│ id │ name │ email │ age │
│────│─────────│─────────────────│──────│
│ 1 │ Alice │ alice@email.com │ 25 │
│ 2 │ Bob │ bob@email.com │ 30 │
│ 3 │ Charlie │ charlie@mail.io │ 22 │
└───────────────────────────────────────┘Popular Databases
| Database | Best For |
|---|---|
| MySQL | Web apps, WordPress |
| PostgreSQL | Advanced features, data integrity |
| SQLite | Mobile apps, small projects |
| SQL Server | Enterprise, Microsoft stack |