SELECT DISTINCT is often a code smell. (Not always.) If you see it, there’s a 70% chance it got slapped on to fix an issue that should have been solved a different way.
SELECT DISTINCT ON is different, and useful.
SELECT DISTINCT ON is different, and useful.
- For a question worth 2 points, if you use the word "DISTINCT" when it wasn't needed, you lose 0.5 points.
- If you don't use "DISTINCT" when it was necessary, you lose all 2 points.