SQL COUNT Column

Counting a specific column only counts its non-NULL values — this is where it diverges from COUNT(*).

What & Why

COUNT(column_name) counts only the rows where that column has an actual, non-NULL value. Rows where it's NULL are skipped entirely.

BUSINESS QUESTION

Count only product feedback rows that contain an NPS score.

id	user_id	feature_id	rating	nps_score	comment	created_at
1	101	1	5	9	Clear and useful	2024-01-25 12:15:00+00
2	102	2	4	NULL	Export worked well	2024-02-20 15:40:00+00
3	103	1	4	7	Helpful setup flow	2024-03-18 09:05:00+00
4	104	3	3	NULL	Needs clearer timing	2024-04-08 17:30:00+00

EXAMPLE QUERY

SELECT COUNT(nps_score) AS scored_feedback
FROM product.feedback;

RESULT — NULL scores are skipped

scored_feedback
2

Two of the four product.feedback rows contain an nps_score.