SQL GROUP BY One Column

The simplest, most common shape — one column decides the groups, one aggregate summarizes each one.

What & Why

Grouping by a single column is by far the most common pattern you'll write — "total X per Y" or "average X per Y" questions almost always start here. The previous lesson walked through the full mechanics; this lesson is about recognizing the pattern quickly and applying it directly.

The shape is always the same: SELECT grouping_column, aggregate(other_column) FROM table GROUP BY grouping_column. Once that structure feels automatic, reaching for it becomes second nature.

See How It Works

BUSINESS QUESTION

Growth wants one user count for each acquisition channel.

id	created_at	country	channel	plan	activated_at	churned_at
101	2024-01-15 09:10:00+00	US	organic	pro	2024-01-16 14:25:00+00	NULL
102	2024-02-10 11:05:00+00	CA	paid	free	NULL	2024-03-20 10:00:00+00
103	2024-03-12 16:35:00+00	GB	referral	pro	2024-03-13 08:15:00+00	NULL
104	2024-04-01 13:20:00+00	US	organic	free	2024-04-03 12:00:00+00	NULL

EXAMPLE QUERY

SELECT
  channel,
  COUNT(*) AS user_count
FROM growth.users
GROUP BY channel
ORDER BY user_count DESC, channel;

RESULT — exact output from the displayed Queryflo rows

channel	user_count
organic	2
paid	1
referral	1

The four growth.users rows form three real channel groups.

Now You Try

Practice this concept

Growth wants one user count for each acquisition channel.

Available schema

growth

Prefix tables with growth.table_name.

channeluser_count

growth.users

Column	Type
id	integer
created_at	timestamp with time zone
country	text
channel	text
plan	text
activated_at	timestamp with time zone
churned_at	timestamp with time zone
legacy_user_code	text

query.sql

Intermediate business practice