The requirement for a final ELSE clause is defensive programming. The clause should either take appropriate action, or contain a
suitable comment as to why no action is taken.
Noncompliant code example
SELECT
CASE category
WHEN 'A' THEN 21
WHEN 'B' THEN 33
END shipping_cost
FROM product
Compliant solution
SELECT
CASE category
WHEN 'A' THEN 21
WHEN 'B' THEN 33
ELSE 42
END shipping_cost
FROM product
