Aggregation intro

Draft

Aggregates reduce many rows into summaries. GROUP BY decides the level of detail: one row for the whole table, or one row per group.

Count and sum

Aggregate functions collapse many rows into one summary row.

SELECT COUNT(*) AS orders, SUM(total_cents) AS revenue_cents
FROM orders;

Loading plan...

GROUP BY returns one summary row for each distinct city.

SELECT city, COUNT(*) AS orders, SUM(total_cents) AS revenue_cents
FROM orders
GROUP BY city
ORDER BY city;

Loading plan...

HAVING filters grouped rows after the aggregate has been computed.

SELECT status, COUNT(*) AS orders
FROM orders
GROUP BY status
HAVING COUNT(*) > 1
ORDER BY status;

Loading plan...