Firebird 2.1 Language Reference Update

Example:
select name,
age,
case upper(sex)
when 'M' then 'Male'
when 'F' then 'Female'
else 'Unknown'
end,
religion
from people
Searched CASE
Syntax:
CASE
WHEN THEN result
[WHEN THEN result ...]
[ELSE defaultresult]
END
Miscellaneous language elements
Here, the s are tests that give a ternary boolean result: TRUE, FALSE, or NULL. The first expression
evaluating to TRUE determines the result. If no expression is TRUE and there is an ELSE clause, defaultresult
is returned. If no expression is TRUE and there is no ELSE clause, NULL is returned.
As with the simple CASE, the results don't have to be literal values: they may also be field or variable names,
compound expressions, or NULL literals.
Example:
CanVote = case
when Age >= 18 then 'Yes'
when Age < 18 then 'No'
else 'Unsure'
end;
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