PostgreSQL - CHR Function

The CHR() function in PostgreSQL is used to convert an integer ASCII code or a Unicode code point into its corresponding character. Let us better understand the concept of CHR Function in PostgreSQL from this article.

Syntax

CHR(value);

Parameter:

• value: The 'value' argument is generally an integer ASCII code or a UTF8 Unicode code point character.

The CHR() function is often used to retrieve the character associated with a given ASCII code or Unicode code point. This can be particularly useful for generating specific characters dynamically or for processing data that involves character codes.

PostgreSQL CHR Function Examples

Let us look at some of the examples of CHR Function in PostgreSQL to better understand the concept.

Example 1: Converting ASCII Codes to Characters

The following statement shows how to use the CHR() function to get the characters whose ASCII code value is 100 and 200:

SELECT CHR(100), CHR(200);

Output:

Explanation: In this example, CHR(100) returns the character 'd', which corresponds to the ASCII code 100. CHR(200) returns a character based on the extended ASCII table, which might vary depending on the system's character set encoding.

Example 2: Converting Additional ASCII Codes to Characters

The following statement shows how to use the CHR() function to get the characters whose ASCII code value is 52 and 87:

SELECT CHR(52), CHR(87);

Output:

Explanation: In this query, CHR(52) returns the character '4', and CHR(87) returns the character 'W', corresponding to their respective ASCII codes.

Important Points About PostgreSQL CHR Function

• The CHR() function supports Unicode code points, allowing you to convert integers representing Unicode characters to their respective UTF8 characters.
• PostgreSQL CHR() function can handle extended ASCII values (128-255) based on the system's encoding.
• The CHR() function can generate control characters (ASCII values 0-31). These characters are often non-printable and used for control purposes in data streams.
• You can use the CHR() function in combination with the ASCII() function to perform round-trip conversions between characters and their ASCII codes.