Introduction to CTEs

CTEs (Common Table Expressions) name a subquery for reuse.

WITH high_earners AS (
    SELECT * FROM employees WHERE salary > 90000
)
SELECT * FROM high_earners;

Benefits:

• More readable than nested subqueries
• Can reference multiple times
• Self-documenting code
• Easier to debug

Start with WITH, name your CTE, define it in parentheses.