Summarize groups with GROUP BY and HAVING

GROUP BY collects rows with the same key so COUNT, SUM or AVG can summarize them. WHERE filters rows before grouping; HAVING filters groups after aggregation.

SELECT category, COUNT(*) AS product_count FROM products GROUP BY category HAVING COUNT(*) >= 2;

Common misunderstanding

An unaggregated product name does not represent an entire category. Return a grouping key or an aggregate expression.

Related missions

• Practice: Count products by category
• Practice: Find top customers

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