Can you mix window functions and GROUP BY?

Question

Accepted Answer

Window functions are evaluated in the SELECT phase, which happens after GROUP BY has already reduced the rows. So by the time COUNT(*) OVER () runs, it sees one row per group - not the original employee rows. To count original rows per group alongside a GROUP BY aggregate, use COUNT(*) as a regular aggregate in the same GROUP BY query. If you need both individual rows and group aggregates, use a window function without GROUP BY - that is the whole point of PARTITION BY.