PL/SQL Associative Arrays - Index Not In Array

Say I have an associative array 'blah' and it has members 'hello' and 'bye.'

How can I instruct Oracle to return a NULL if I lookup the array and the value isn't found?

E.g.
blah('hello') might map to '1'
But I want blah('Oracle') to return NULL. Received on Thu Jun 09 2005 - 03:07:24 CDT