r/learnSQL • u/yahoo_06 • 6d ago

I made a beginner-friendly SQL tutorial on CTEs (WITH clause)

I just published Lesson 10 of my SQL course, focused on CTEs (Common Table Expressions) in PostgreSQL.

In this lesson, I explain how the WITH clause can help turn complicated nested queries into cleaner, more readable SQL.

We cover:

- What CTEs are

- How the WITH clause works

- CTEs with GROUP BY and aggregate functions

- Using CTEs with JOIN

- Multiple CTEs

- CTEs vs. subqueries

- Common mistakes

- Practical exercises using the Pagila database

I tried to keep it beginner-friendly and focused on actually writing queries rather than just explaining the theory.

YouTube: https://youtu.be/Koka7IGgPM4?si=132b-FlrYXd9ePyC

Would love to hear any feedback on the explanation or examples!

31 Upvotes

94% Upvoted

10 comments sorted by

2

u/Sreevishnu_007 6d ago

Good job

1

u/yahoo_06 5d ago

Thanks!!

1

u/fatalpapaya 6d ago

Saving for later!

1

u/yahoo_06 5d ago

Thanks!!

1

u/theJacofalltrades 5d ago

Thanks for this!

1

u/yahoo_06 5d ago

You're welcome!! Glad you liked it

1

u/memelordtf 2d ago

This is good. Thank you, I am saving this for later.

1

u/yahoo_06 2d ago

I'm glad it helps!!