Reordering items in a report

Question

The scenario: I have a table that holds values and their respective position "in line".
For example, Apples = 1, Bananas = 2, Oranges = 3, Grapes = 4. When I display a report, I want the values to show up in order...so, Apples, Bananas, Oranges, Grapes.
I need to add the capability to allow the user to rearrange the position (order) that is stored in the database by inserting one of the values before another value. So, If the user wants Grapes before Bananas, they need to be able to enter that, have the database be updated, and have the page repost itself so the user can see the changes.
Any basic ideas how to accomplish this?

Answer 1

How do I process these changes so that the changes
are saved?Hm? The page we are talking about is a wizard-generated tabular form on a table. The wizard already creates MRU (multi-row update/delete) processes and Save/Delete buttons. Don't you already have all this setup?
I have a column in my table called POSITION that is
supposed to store the ordering.Right, that corresponds to the SEQ column in my example.
Where does it go?:
create table emp_up_down as select * from emp;
alter table emp_up_down add (seq integer unique
deferrable initially deferred);
update emp_up_down set seq=rownum;I showed a self-contained fully-working example on that other thread. Something anyone could take, understand and modify according to their specific requirements. So, no, I doubt you would need the exact same code I posted!
Those 3 SQL statements just create a table, add a SEQ column to it and populate it. You probably already have all this.
The important thing I wanted to point out was that the unique constraint on the SEQ (POSITION or whatever) column needs to be "deferrable initially deferred". Why? Because to swap the value of that column in 2 rows, the MRU process would do this in 2 UPDATE statements and after the first UPDATE statement, the unique constraint would be violated. By making it deferrable, we are asking Oracle to ignore the violation until a COMMIT is issued. A COMMIT would be done after all the updates are done and at that time, the SEQ column would be unique again.
Hope this helps.