SQL HAVING

Filters GROUPS after aggregation — the tool that finally makes 'channels where the average spend exceeds X' possible.

What & Why

WHERE filters individual rows, and it runs before grouping even happens — which means WHERE has no way to reference an aggregate result like AVG(spend), since that value doesn't exist yet at the point WHERE runs. HAVING solves this: it filters groups, after aggregation has already been computed, so conditions like "keep only groups where the average exceeds 50000" become possible for the first time.

Think of it this way: WHERE decides which raw rows are even allowed into the grouping process. HAVING decides which already-formed, already-summarized groups make it into the final output. They operate at two completely different stages of the query.

See How It Works

BUSINESS QUESTION

Marketing wants only channels with meaningful spend.

id	name	channel	spend	start_date	end_date	status	target_segment
1	Spring Launch	google_ads	55000.00	2024-01-15	2024-03-31	active	smb
2	Retention Webinar	email	45000.00	2024-02-10	2024-04-15	active	enterprise
3	Finance Retargeting	linkedin	50000.00	2024-03-12	2024-05-31	active	enterprise
4	Enterprise Search	google_ads	60000.00	2024-04-01	2024-06-30	active	enterprise

EXAMPLE QUERY

SELECT
  channel,
  ROUND(SUM(spend), 2) AS total_spend
FROM marketing.campaigns
GROUP BY channel
HAVING SUM(spend) >= 10000
ORDER BY total_spend DESC;

RESULT — exact output from the displayed Queryflo rows

channel	total_spend
google_ads	115000.00
linkedin	50000.00
email	45000.00

HAVING keeps all three completed channel totals because each exceeds 10,000.

Intermediate business practice