SQL · Aggregation and grouping

group by

Collapses rows into groups so aggregates run per group.

sqlRunnable example sql course

Syntax

group by column

Example

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WITH lessons(course, minutes) AS (VALUES ('HTML', 10), ('HTML', 20), ('CSS', 15))
SELECT course, sum(minutes) AS total FROM lessons GROUP BY course;

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