1. What unique PostgreSQL feature allows CTEs to perform writes and feed results into other query steps?
- Using RETURNING in INSERT, UPDATE, or DELETE inside the CTE.
- Declaring temporary tables inside the WITH clause.
- CTEs do not support write operations.
- Using EXPLAIN ANALYZE.
Hint: In PostgreSQL, you can place INSERT/UPDATE/DELETE queries inside a CTE. Appending the 'RETURNING' clause passes the modified rows to subsequent CTEs or the main query.