Part 70: NATURAL JOIN & USING: Convenience vs Production Fragility

1. The USING Clause

When both tables share the exact same column name:

SELECT * FROM orders JOIN users USING (user_id);

2. Why NATURAL JOIN is an Antipattern

NATURAL JOIN automatically joins on all columns that share the same name: - If both tables happen to have created_at or status columns, it will silently join on those too! - A schema migration adding a column can silently break existing queries.

Key Takeaways

• Always use explicit ON a.id = b.a_id in production code.

In Part 71, we enter Module 8 to explore Subqueries: Scalar, Column, and Table Subqueries!