According to the book I am reading ORDBMSs come with an option to write a program (method) in Java (or other programming language), compile it into Java byte code and register via some SQL command.
For example, the ORDBMS may handle Java code in the Linux operating system. In this case, the method code must be written in Java and compiled into a Java bytecode file stored in a Linux file system. Then an SQL style method registration command is given to the DBMS so that it recognizes the new method:
**CREATE FUNCTION is_sunrise(jpeg_image) RETURNS boolean AS EXTERNAL NAME '/a/b/c/dinky.class' LANGUAGE 'java';**
I'd love to see some example of this written in Java or C++ or any other language. MySQL docs don't contain much information.