ASCII_CHAR (<code>)
<code> ::= an integer in the range [0..255]
Important:
If the external function ASCII_CHAR is declared in your database, it will override the internal function. To make the internal function available, DROP or ALTER the external function (UDF).
If you are used to the behaviour of the ASCII_CHAR UDF, which returns an empty string if the argument is 0, please notice that the internal function correctly returns a character with ASCII code 0 here.