Why JOIN USING Can Lead to Errors in SQL

This article discusses the risks of using JOIN USING syntax in SQL, particularly in production environments. It begins by contrasting NATURAL JOIN with JOIN USING, showing how NATURAL JOIN can accidentally join on unintended columns like LAST_UPDATE. While JOIN USING seems cleaner for ad-hoc queries, the article demonstrates a concrete example where adding a new column to a table via ALTER TABLE introduces ambiguity and breaks existing queries. It concludes that JOIN ON is safer for production code, as it avoids such schema evolution issues, while JOIN USING remains acceptable for quick ad-hoc SQL.