SQL CASE ELSE

Supplies a fallback value for rows that don't match any WHEN condition — without it, non-matching rows silently become NULL.

What & Why

ELSE value goes right before END, and it's what a row falls back to when none of the WHEN conditions above it matched. Without an explicit ELSE, that fallback is always NULL — which the CASE WHEN lesson touched on briefly. This lesson is about replacing that default with something more useful.

See How It Works

BUSINESS QUESTION

Product wants every feedback rating classified, including ratings outside the positive rule.

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
  id AS feedback_id,
  rating,
  CASE WHEN rating >= 4 THEN 'positive' ELSE 'not positive' END AS rating_class
FROM product.feedback
ORDER BY feedback_id;

RESULT — exact output from the displayed Queryflo rows

feedback_id	rating	rating_class
1	5	positive
2	4	positive
3	4	positive
4	3	not positive

ELSE gives the final feedback row an explicit fallback label.

Now You Try

Practice this concept

Product wants every feedback rating classified, including ratings outside the positive rule.

Available schema

product

Prefix tables with product.table_name.

feedback_idratingrating_class

product.feedback

Column	Type
id	integer
user_id	integer
feature_id	integer
rating	integer
nps_score	integer
comment	text
created_at	timestamp with time zone
moderation_bucket	text

query.sql

Intermediate business practice