DevJourney SQL ยท blogWriting about learning SQL and PostgreSQL: queries, the errors the database raises, and working with real data.https://devjourney.app/en-usColumn must appear in the GROUP BY clause: what it meanshttps://devjourney.app/en/sql/blog/must-appear-in-group-by-clause/https://devjourney.app/en/sql/blog/must-appear-in-group-by-clause/Adding the column to GROUP BY silences PostgreSQL and changes the question. On the same data, the fixed query drops a customer who spent 590.Mon, 26 Oct 2026 00:00:00 GMTbledydebugowanieArtur Kot