Setting Up Your Environment

Before writing SQL, you need a place to run it. In this lesson, we'll set up a free, browser-based SQL environment so you can follow along with every lesson.

Option 1: SQLiteOnline (Recommended for Beginners)

The easiest way to get started is sqliteonline.com — a free, browser-based SQL editor. No installation required.

1. Go to sqliteonline.com
2. Click SQLite in the left panel
3. You'll see an editor where you can type SQL on the left and see results on the right

Option 2: DB Fiddle

DB Fiddle lets you choose between SQLite, MySQL, and PostgreSQL. Great for testing compatibility across databases.

Option 3: Install PostgreSQL Locally

If you want to install a real database locally:

# macOS (using Homebrew)
brew install postgresql@16
brew services start postgresql@16

# Ubuntu / Debian
sudo apt-get install postgresql postgresql-contrib
sudo systemctl start postgresql

# Windows
# Download installer from postgresql.org/download/windows

Connecting with psql

psql is the PostgreSQL interactive terminal — a command-line client that ships with every PostgreSQL installation. It lets you connect to a database and run SQL queries directly from your terminal.

PostgreSQL listens on port 5432 by default.

Connect to your local server using the -U flag to specify the username:

psql -U postgres

The -U flag stands for user — it tells psql which database user to authenticate as.

Essential psql Meta-Commands

Once inside psql you interact with it using meta-commands (also called backslash commands). These are not SQL — they are shortcuts understood only by the psql client.

Command	What it does
\l	List all databases on the server
\c dbname	Connect (switch) to a different database
\dt	Show tables in the current database
\q	Quit the psql terminal

Example session:

postgres=# \l           -- list all databases
postgres=# \c mydb      -- switch to the database called mydb
mydb=# \dt              -- show tables in mydb
mydb=# \q               -- exit psql

GUI Tools for PostgreSQL

If you prefer a graphical interface instead of the terminal, pgAdmin is the most popular free GUI tool for PostgreSQL. It lets you browse databases, run queries, and manage tables through a web-based interface — no command-line required.

Other popular GUI clients include DBeaver and TablePlus.

Option 4: Supabase (Cloud PostgreSQL)