CS5 - Mastering SQL Execution Order with JOINs 🔗

Mastering SQL Execution Order: How Queries Really Run Behind the Scenes

Why Understanding Execution Order Matters?

When writing SQL queries, what you see isn’t always what happens first. SQL processes queries in a specific order, and understanding this can make or break your queries—especially when JOINs enter the scene.

In my previous databites issue, we broke down SQL’s execution order.

But what happens when multiple tables are involved?

That’s what we’ll explore in this article.

SQL Execution Order - Recap

SQL isn’t read top-to-bottom as we write it—it has its own execution order!

Here’s how a basic query is processed:

1️⃣ FROM – Identify the data source 📦
2️⃣ WHERE – Filter rows 🔍
3️⃣ GROUP BY – Group similar data 📊
4️⃣ HAVING – Filter groups ✂️
5️⃣ SELECT – Pick the columns 🎨
6️⃣ ORDER BY – Sort the results 📚
7️⃣ LIMIT – Keep only a certain number of rows 🔢

Simple enough, right? But JOINs introduce a twist! 🌀

But before we start…

Before starting, here you have the full-resolution cheatsheet 👇🏻