Primary key using output of function rather than column

[hrishy]

Hi

This is what i can think of in 9i and above

CREATE TABLE myTable
(
  theNumber NUMBER(6),
  TheLetter char(1)
  CONSTRAINT theNumber_pk primary key(theNumber)
    USING INDEX
    (CREATE UNIQUE INDEX my_pk_idx 
	ON employees(theNumber, NVL2(theLetter, 0, 1))
);

i dont think so you can create a primary key on a column that is non existant like theNumber, NVL2(theLetter, 0, 1)

But 11g i know introduces the concept of Virtual columns but again i am not sure if virtual columns can be part of primary keys.

regards
Hrishy