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 …
Tutorial: Case
— Conditional Expressions
Better supported alternative: case when …
(searched case).
The comma-separated case
expression is defined in ISO/IEC 9075:2016-2 as optional feature F263, “Comma-separated predicates in simple CASE
expression”.
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