SQL Subqueries vs CTEs: A Complete Guide for Data Analysts

If you've been writing SQL for a while, you've probably run into situations where a single SELECT statement just doesn't cut it. You need to filter based on aggregated data, break a complex query into logical steps, or reuse a derived dataset multiple times in the same query.

That's where subqueries and CTEs (Common Table Expressions) come in.

In this article, I'll walk you through both concepts clearly what they are, the different types, when to use each, and how they compare in performance and readability. By the end, you'll know exactly which tool to reach for depending on the situation.

What Is a Subquery?

A subquery (also called an inner query or nested query ) is a SELECT statement written inside another SQL statement.…