SQL Aggregate Functions
Collapse many rows into a single summary value — how many, how much, what's the average.
What & Why
An aggregate function takes a whole column of values and reduces it to one number: a count, a total, an average, a minimum, a maximum. This lesson series covers the five you'll use constantly: COUNT, SUM, AVG, MIN, MAX.
See How It Works
| 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 | 45000.00 | 2024-02-10 | 2024-04-15 | active | enterprise | |
| 3 | Finance Retargeting | 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 COUNT(*) AS campaign_count, AVG(spend) AS avg_spend
FROM marketing.campaigns;RESULT — 4 rows collapsed into 1
| campaign_count | avg_spend |
|---|---|
| 4 | 52500.00 |
The result uses the same Queryflo columns shown in the worked example.
Now You Try
Practice this concept
Marketing wants a one-row email delivery summary with send count, total recipients, and total clicks.
Available schema
marketingPrefix tables with marketing.table_name.
send_counttotal_recipientstotal_clicksmarketing.email_sends| Column | Type |
|---|---|
| id | integer |
| campaign_id | integer |
| sent_at | timestamp with time zone |
| recipients | integer |
| opens | integer |
| clicks | integer |
| unsubscribes | integer |
| bounces | integer |
| legacy_send_group | text |
query.sql
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