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Lesson 5 — COUNT & SUM
COUNT and SUM: one answer from many rows
An aggregate function combines many rows into a single value. COUNT(*) counts rows; SUM(column) adds up a column. You can rename a result with AS to make it readable.
SELECT COUNT(*) AS orders, SUM(total) AS revenue FROM orders
fetchone() returns the single result row as a tuple.
Why it matters: dashboards are mostly aggregates — number of users, total sales, orders today.
Want it another way?
Task
Write the query that returns COUNT(*) and SUM(total) from orders. Expected: (4, 100.0).
Run your code — when the output matches the task, you will see a green check. Then mark the lesson complete.
Test your knowledge
Test your knowledgeA quick 3-question quiz on this lesson — instant feedback.