Firebird 2.1 Language Reference Update

Examples:
Miscellaneous language elements
update People set AgeCat = 'Old'
where BirthDate < date '1-Jan-1943'
insert into Appointments
(Employee_Id, Client_Id, App_date, App_time)
values
(973, 8804, date 'today' + 2, time '16:00')
new.lastmod = timestamp 'now';
See also: CAST
Available in: DSQL, PSQL
Added in: 1.5
CASE construct
Description: A CASE construct returns exactly one value from a number of possibilities. There are two syntactic
variants:
• The simple CASE, comparable to a Pascal case or a C switch.
• The searched CASE, which works like a series of “if ... else if ... else if” clauses.
Simple CASE
Syntax:
CASE
WHEN THEN result
[WHEN THEN result ...]
[ELSE defaultresult]
END
When this variant is used, is compared to 1, 2 etc., until a match is found, upon
which the corresponding result is returned. If there is no match and there is an ELSE clause, defaultresult
is returned. If there is no match and no ELSE clause, NULL is returned.
The match is determined with the “=” operator, so if is NULL, it won't match any of the s,
not even those that are NULL.
The results don't have to be literal values: they may also be field or variable names, compound expressions,
or NULL literals.
A shorthand form of the simple CASE construct is the DECODE() function, available since Firebird 2.1.
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