Subqueries vs. CTEs in SQL: A Practical Guide to Writing Cleaner, Smarter Queries Whether you're just getting comfortable with SQL or leveling up your data skills, two tools will come up again and again when working with complex queries: subqueries and Common Table Expressions (CTEs) . They solve similar problems — breaking a complex query into manageable pieces — but they do it in different ways, and knowing when to use each one is the mark of a confident SQL developer. This article gives you a complete picture of both: what they are, how they work, when to use them, and how to choose between them. What Is a Subquery? A subquery (also called an inner query or nested query) is a SQL query written inside another query. The outer query uses the result of the inner query as part of its logic. Think of it like a Russian nesting doll: the database runs the inner query first, produces a result, and then the outer query works with that result.…