To provide a dynamic way for performing user specific actions when a database related error occurs at program execution time. Transactional and connection errors are detected and a user-defined routine is executed.
Is the name of a subroutine contained in the program using this rule. This parameter is optional.
The error_handler command is procedural and the subname parameter is optional. If specified, the subroutine becomes the new error_handler until the program ends or a different error_handler is executed (in the same program). When the subname parameter is not specified, the error handling routine is reset to the one specified by the error_handler rule or, to the default error_handler if no error_handler rule exists.
More information at Error_Handler Rule