Resolving 'Ambiguous column'

What You Will Learn

• Prefix column names with table aliases in JOIN queries.
• Avoid SELECT * when tables share column names like id or created_at.
• Review USING clauses to ensure the intended column is shared.

Sample SQL

SELECT o.id, o.created_at, u.name
FROM orders o
JOIN users u ON u.id = o.user_id
WHERE o.created_at >= '2026-01-01';

Next Step

Try rewriting this query in your own schema, then use our tools to format and refine it.