CASE WHEN a THEN b ELSE c END

DECLARE @n INT
SET @n=124
print CASE WHEN @n=123 THEN 'equal' ELSE 'not equal' END

--If/ElseIf expression
SET @n=5
print CASE WHEN @n=3 THEN 'Three' WHEN @n=4 THEN 'Four' ELSE 'Other' END