"Where" filters rows before any grouping or aggregation is done,you cannot use aggregate functions (like AVG, COUNT, etc.) directly in the "WHERE" clause because the aggregation happens after the filtering is done. "Having" is used specifically to filter groups created by GROUP BY based on aggregate functions. In Lab4 Q3 Having allows filtering based on the result of an aggregate function AVG(), because HAVING clause applies after the GROUP BY. So I don' think you can use Where instead of GROUP BY + HAVING in this case. Sometimes your query with WHERE might have returned the correct results, but the proper SQL structure should involve GROUP BY and HAVING in this case.