Can not user Raw value as NULL return in Select List

Question

Help me!
I recently converted my application to take advantage of the sys_guid() function that oracle offers over the sequence/trigger option.
However, I user a hierarchical set up and I need to be able to insert a RAW value of '00' if the user does not select something in a select list. When I try to do this, I get an "ORA-01465: invalid hex number" error.
I've also tried to return 00 and HEXTORAW(0) but that didn't work either. Infact 00 return a can not insert null value. Please help as I believe the sys_guid function is the best choice if I can make it work.

Answer 1

Hey Scott, my first name is Daniel.
Here is in detail the reason for which I want to be able to work with RAW. As everyone knows, most of your tables your going to have a UID. In general this is going to be a NUMBER column into which you will insert values that populate from a trigger getting the nextval of a sequence and returning the result into the NUMBER column of the row being inserted.
This, however, requires a trigger and a sequence. Not that that's really a bad thing, I just think it can be done better. All we are really after here is a UUID or GUID. The thing is if you used a sequence to generate this value, you don't have a good way of knowing that the number is truly unique. You'll learn this as soon as you try to merge with a table from another database or do something else of the like.
What I prefer to do is to use Oracle's SYS_GUID function when I create a table. To use this function you create a RAW(16) DEFAULT SYS_GUID(). From that point you don't even need to reference the column on insert, unless you're inserting into * and in that case you just specify DEFAULT. The use of sys_guid means I don't need a trigger and I don't need a sequence, and the result will always be unique, regardless of the DB.
In APEX, and elsewhere, the way you use a select list is with a display value and a return value. An example would be, emp_name as the display value and emp_id as the return value. In my case, the emp_id would be the RAW values returned by the SYS_GUID() function when the employee was created. But it's not working because of the RAW value.
I know that APEX can enter the value in session state that is returned from a RAW column because I did a test earlier and it worked. I would have to see it in session state for debugging. *** The problem is in creating a new record. ***
APEX really does not have to work with the RAW column because the default value has been specified. But for some reason, it does not like it anyway. I found this problem when working with parent/child relationships in my tables.
Lets say there are three columns GUID, TITLE, and PARENT. When creating a new record, I allow the user to select its parent. If the new record IS a parent then they would leave it as the default '- Is Parent -' and the PARENT column would be left as NULL. But because the GUID is RAW to make the relationship work with the parent, the PARENT column would be RAW too and APEX gives me the errors I was telling you about before.
Sorry for going on so long. I don't know if I even got my point across. ;) Please let me know if you need me to do something on my part to further demonstrate my point. I would be happy to set up a demo if requested.