Why must aggregate functions be used with GROUP BY?

< 1 min read

Aggregate functions summarize multiple rows into a single value like total or count.
GROUP BY defines how those rows should be grouped before aggregation.
Without GROUP BY, aggregates would apply to the entire dataset.
In reporting, we need aggregates at a specific business level.
In my project, SUM(sales) with GROUP BY month gave monthly revenue.
It ensures aggregates align correctly with dimensions.
This avoids incorrect or misleading summary results.

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