Aggregation

What it is

Aggregates compute count, sum, min, max, or average.

When to use it

Build reports within one currency and defined status.

Syntax

COUNT(*) | SUM(amount_cents) | MIN(amount_cents) | MAX(amount_cents)

Example

SELECT currency, COUNT(*) AS count, SUM(amount_cents) AS settled_cents
FROM transactions WHERE status = 'settled'
GROUP BY currency;

Common mistakes

Do not sum different currencies; SUM over no rows returns NULL; AVG may return a noninteger.

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