The simple form of case
allows one expression in the when clause. With the comma-separated form, it accepts a list of expressions.
SELECT CASE column_name WHEN 0, 1, 2 THEN 'good'
WHEN 3, 7, 9 THEN 'bad'
END
FROM …
Related
Tutorial:
Case
— Conditional ExpressionsBetter supported alternative:
case when …
(searched case).
Normative References
The extended case
expression is defined in ISO/IEC 9075:2016-2 as optional feature F263.