SQL · Aggregate functions

sum(case …)

Counts rows that match a condition using only standard aggregate syntax.

sqlRunnable example sql course

Syntax

sum(case when … then 1 else 0 end)

Example

Open in the lab

WITH lessons(minutes) AS (VALUES (5), (15), (30))
SELECT sum(CASE WHEN minutes >= 10 THEN 1 ELSE 0 END) AS long_lessons FROM lessons;

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