Firebird 2.1 Language Reference Update

Internal functions
This will return the average weight of the persons listed in FatPeople, excluding those having a weight of -1,
since AVG skips NULL data. Presumably, -1 indicates “weight unknown” in this table. A plain AVG(Weight)
would include the -1 weights, thus skewing the result.
Note
In Firebird 1.0.x, where NULLIF is not available, you can accomplish the same with the *nullif external
functions.
Available in: DSQL, PSQL
Added in: 2.0
Changed in: 2.1
OCTET_LENGTH()
Description: Gives the length in bytes (octets) of the input string. For multi-byte character sets, this may
be less than the number of characters times the “formal” number of bytes per character as found in RDB
$CHARACTER_SETS.
Note
With arguments of type CHAR, this function takes the entire formal string length (e.g. the declared length of a
field or variable) into account. If you want to obtain the “logical” byte length, not counting the trailing spaces,
right-TRIM the argument before passing it to OCTET_LENGTH.
Result type: INTEGER
Syntax:
OCTET_LENGTH (str)
BLOB support: Since Firebird 2.1, this function fully supports text BLOBs of any length and character set.
Examples:
select octet_length('Hello!') from rdb$database
-- returns 6
select octet_length(_iso8859_1 'Grüß di!') from rdb$database
-- returns 8: ü and ß take up one byte each in ISO8859_1
select octet_length
(cast (_iso8859_1 'Grüß di!' as varchar(24) character set utf8))
from rdb$database
-- returns 10: ü and ß take up two bytes each in UTF8
select octet_length
(cast (_iso8859_1 'Grüß di!' as char(24) character set utf8))
from rdb$database
-- returns 26: all 24 CHAR positions count, and two of them are 2-byte
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