SQL Common Table Expressions (CTEs): Simplify Complex Queries

Common Table Expressions (CTEs) create temporary named result sets that you can reference within your query. They make complex queries more readable by breaking them into logical steps.

Syntax: WITH cte_name AS (SELECT ...) SELECT * FROM cte_name. Multiple CTEs can be defined: WITH cte1 AS (...), cte2 AS (...) SELECT ... Each CTE can reference previous ones.

CTEs are especially useful for: breaking down complex joins, performing recursive queries (hierarchies, sequences), and improving readability of analytical queries.

Recursive CTEs reference themselves: WITH RECURSIVE cte AS (base_case UNION ALL recursive_case) SELECT * FROM cte. Use them for organizational hierarchies, number sequences, or traversing graph data.

Practice CTEs in CompileZ's SQL editor. Rewrite complex queries using CTEs to see how they improve readability.