Count by Category — Solution & ExplanationProblems / Count by Category / EditorialApproachThis is the most fundamental aggregation pattern:

GROUP BY category to create one bucket per distinct category value.

COUNT(\*) to count the rows in each bucket.

ORDER BY category for deterministic output.

Key ConceptCOUNT(*) counts all rows in a group regardless of NULL values, while COUNT(column) only counts non-NULL values.Hints

Use GROUP BY to group rows sharing the same category.

COUNT(*) counts the number of rows in each group.