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 Procedural SQL (PSQL) StatementsAggregate Functions 

CHAR_LENGTH Examples

select char_length('Hello!') from rdb$database
-- returns 6

select char_length(_iso8859_1 'Grüß di!') from rdb$database
-- returns 8

select char_length
  (cast (_iso8859_1 'Grüß di!' as varchar(24) character set utf8))
from rdb$database
-- returns 8; the fact that ü and ß take up two bytes each is irrelevant

select char_length
  (cast (_iso8859_1 'Grüß di!' as char(24) character set utf8))
from rdb$database
-- returns 24: all 24 CHAR positions count
See also

[fblangref50-scalarfuncs-bit-length], [fblangref50-scalarfuncs-octet-length]

CRYPT_HASH()

Cryptographic hash

Result type

VARBINARY

Syntax
CRYPT_HASH (value USING <hash>)

<hash> ::= MD5 | SHA1 | SHA256 | SHA512
Table 1. CRYPT_HASH Function Parameter
Parameter Description

value

Expression of value of any type;non-string or non-binary types are converted to string

hash

Cryptographic hash algorithm to apply

CRYPT_HASH returns a cryptographic hash calculated from the input argument using the specified algorithm.If the input argument is not a string or binary type, it is converted to string before hashing.

This function returns a VARBINARY with the length depending on the specified algorithm.

Note

  • The MD5 and SHA1 algorithms are not recommended for security purposes due to known attacks to generate hash collisions.These two algorithms are provided for backward-compatibility only.

  • When hashing string or binary values, take into account the effects of trailing blanks (spaces or NULs).The value 'ab' in a CHAR(5) (3 trailing spaces) has a different hash than if it is stored in a VARCHAR(5) (no trailing spaces) or CHAR(6) (4 trailing spaces).

    To avoid this, make sure you always use a variable length data type, or the same fixed length data type, or normalize values before hashing, for example using TRIM(TRAILING FROM value).