Contents
chr()
A function for converting an integer into a character
chr() is a system function converting an integer into an ASCII or UTF8 character.
chr() was added in PostgreSQL 7.1.
Usage
chr (integer) →text
When using the UTF8 encoding, the integer parameter is considered as a Unicode code point. In other encodings the parameter must represent an ASCII character.
0 is not permitted as it cannot be stored by text data types.
An error is raised if an invalid input parameter value is provided.
Change history
- PostgreSQL 9.4
- now only accepts values that are valid UTF8 characters according to RFC 3629 (commit 7894ac50)
- PostgreSQL 7.1
Examples
Basic usage example for chr():
postgres=# SELECT chr(97); chr ----- a (1 row)
Returning a Unicode character using its UTF8 code point:
postgres=# SELECT chr(12354); chr ----- あ (1 row)
In a non-UTF8 database, only valid ASCII values can be provided:
locale_test=# \l locale_test
List of databases
Name | Owner | Encoding | Collate | Ctype | Access privileges
-------------+----------+----------+----------------+----------------+-------------------
locale_test | postgres | LATIN1 | de_DE.iso88591 | de_DE.iso88591 |
(1 row)
locale_test=# SELECT chr(12354);
ERROR: requested character too large for encoding: 12354
The same applies when the client encoding is not UTF8:
postgres=# SET client_encoding TO latin1; SET postgres=# SELECT chr(12354); ERROR: character with byte sequence 0xe3 0x81 0x82 in encoding "UTF8" has no equivalent in encoding "LATIN1"
0 cannot be provided:
postgres=# SELECT chr(0); ERROR: null character not permitted
References
- PostgreSQL documentation: Other String Functions