SQL & PostgreSQL · Backend Development

Explanation

Relational tables, primary keys, joins, and indexes are the backbone of most production backends.

Code example

sql

CREATE TABLE users (
  id UUID PRIMARY KEY,
  email TEXT UNIQUE NOT NULL,
  created_at TIMESTAMPTZ DEFAULT now()
);

SELECT u.email, count(s.id) AS skills
FROM users u
LEFT JOIN skills s ON s.user_id = u.id
GROUP BY u.email;

Helpful resources

PostgreSQL documentation
Official PostgreSQL docs.
DocumentationFreeOfficial90 min
SQL course — freeCodeCamp
Full SQL course on YouTube.
YoutubeFree240 min

Exercise

Model users and skills with a foreign key, insert rows, and write a JOIN that lists skills per user.

Your notes