SQL · Aggregation and grouping

rollup

Adds subtotal rows for the grouping hierarchy. PostgreSQL only.

sqlRunnable example sql course

Syntax

group by rollup (a, b)

Example

Open in the lab

-- PostgreSQL
-- SELECT course, level, count(*) FROM lessons GROUP BY ROLLUP (course, level);

Reference pages are the quick answer. The course explains the why, shows the full example and ends with a challenge.