SQL Subqueries and CTEs Explained: When One Query Is Not Enough

A tutorial on DEV Community uses a fictional student, Franklin, to explain advanced SQL concepts beyond basic JOINs and SELECT statements. The article introduces subqueries — queries nested inside other queries — as a solution when data must be calculated before it can be used in a comparison. A practical example demonstrates how to find students scoring above the class average without manually hardcoding the average value. By embedding an AVG or MAX function as an inner query inside a WHERE clause, SQL dynamically computes and applies the result in a single statement. The piece is part of an ongoing SQL learning series covering DDL, DML, JOINs, and now subqueries and CTEs.