What is SQLite?

SQLite is the most widely deployed database engine in the world. Unlike client-server databases such as PostgreSQL or MySQL, SQLite is a library embedded directly into your application. There is no separate server process, no configuration, and no installation.

Where is SQLite Used?

SQLite is literally everywhere:

iOS and Android — Every app that stores local data uses SQLite. Your contacts, messages, and photos are stored in SQLite databases.
Firefox — Bookmarks, history, cookies, and extensions are SQLite databases.
Python — The sqlite3 module is part of the standard library. No installation needed.
Bun — Built-in bun:sqlite with a fast native API.
Browsers — Web SQL (deprecated but widely used), IndexedDB internals.
Embedded systems — Airplanes, cars, medical devices.

According to its author D. Richard Hipp, there are likely more than one trillion SQLite databases currently in active use.

SQLite vs. Traditional Databases

Feature	SQLite	PostgreSQL/MySQL
Server	None (embedded)	Separate process
Setup	Zero	Installation + config
File	Single `.db` file	Multiple data files
Concurrency	Single writer	Multiple writers
Scale	Millions of rows	Billions of rows
Use case	Local/embedded	Server/multi-user

SQLite is not trying to compete with server databases. It excels at a different set of problems: local storage, embedded applications, testing, prototyping, and small-to-medium datasets.

SQL Compatibility

SQLite supports most of standard SQL. The syntax you learn here — SELECT, WHERE, JOIN, GROUP BY, window functions, CTEs — works in PostgreSQL and MySQL too, with minor variations.

The key SQLite-specific things to know:

Type system is flexible (type affinity rather than strict types)
Uses INTEGER PRIMARY KEY instead of SERIAL
Has json_extract() for JSON, pragma_table_info() for schema inspection

The Exercise Database

Throughout this course, you will work with a sample store database:

Table	Columns
`products`	id, name, price, category
`users`	id, name, email
`customers`	id, name, email
`orders`	id, customer_id, product_id, quantity, total

Your Task

Select all columns from the products table to see what data we are working with.

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