How do I obtain the next number for a Primary Key using an ADF View Object?

Question

I have two separate View Objects (A & B) for the same Entity Object. View Object A does a SELECT on all of the fields in the table. This View Object is where I execute my adds and updates. View Object B is only used to retrieve the next number for the primary key. This is done so that when I add a row to the database, I always get the max number of the primary key and add one to it. I accomplished this by setting the SQL mode to Expert and using the SQL: "SELECT MAX(NBR) AS MAX_NUMBER FROM TABLE_1". This may be overkill having a seperate View Object for this, but so far this is the only way I have found to obtain the next number. However, I have discovered that this way does not always work.
The problem I'm running into is when I try to add multiple records to View Object A without committing the transaction between each add. Because View Object B is disconnected from View Object A, the MAX_NUMBER of View Object B comes back with the same number for each add I do on View Object A. So I know I must retrieve the MAX_NUMBER from View Object A.
I've tried using the following code in my Table1ViewImpl class:
this.setQuery("SELECT MAX(Table1.NBR) AS MAX_NUMBER FROM TABLE_1 Table1");
this.executeQuery();
The view object now has what I want, but I have yet to figure a way to extract the MAX_NUMBER out of the View Object. I've also looked into using the method addDynamicAttribute() but I can't figure out any way to set the attribute with the MAX_NUMBER.
I can't be the only one trying to retrieve the next number from a database table using ADF. Can anyone help me with this? FYI - I'm using JDev 10.1.3 EA.

Answer 1

You missing the point.
On a multi-user db knowing the next highest number doesn't guarantee the number will be available when it comes time to commit the record. You can prove this to yourself by opening two instances of your app and do whatever you do to add a new record to your VO. Both will assume the same number, and when you commit an error will be generated
You must use sequences to avoid the possibility of duplicate keys. If you are trying to avoid gaps in your numbering then you need to convince yourself why this is necessary.