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 <Expression> 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 comma-separated case expression is defined in ISO/IEC 9075:2016-2 as optional feature F263, “Comma-separated predicates in simple CASE expression”.
