When is GROUP BY not needed when using COUNT(*)?

The GROUP BY clause is used to aggregate rows that share the same values in specified columns. When you use COUNT() without any GROUP BY clause, the query counts all rows in the table or the result set of a preceding WHERE filter. In this case, there is no need to group the rows because you are computing a single aggregate value for the entire set. GROUP BY becomes necessary only when you want separate counts for each distinct value of one or more columns. For example, SELECT department, COUNT() FROM employees GROUP BY department; returns a count per department. If you omit GROUP BY, you would get a single count for all employees. Thus, GROUP BY is not needed when the aggregation is intended to produce a single result for the entire dataset.