APEX

I have a tabular form on HR schema's Employees table.
On the Department Field I want to place an Popup LOV (not select list).
But the problem is since the table has department ID field and not the department name, the LOV has to return Department ID although it shows Department name when the LOV is open.
I don't want to show department ID on form but want to show department name. And department ID should be on the back (hidden field). Therefore I made an extra column with the name DEPARTMENT which is non-database column (no table reference)
I wrote a a process which fires On Submit after validation and computation which seeks department_id from the table on the basis of what was selected from the list and assigns department id to the hidden field in the tabular form.

The problem comes when I try to submit the form it raises an error

Error in mru internal routine: ORA-20001: Error in MRU: row= 0, ORA-20001: ORA-20001: Current version of data in database has changed since user initiated update process. current checksum = "4EB6AAF3C9315880CCB50CD7E9F580D7", item checksum = "C6D68DEE14C198A67CAF47BA7CADB9E8".,



Line: -----
My code of the process is


DECLARE
v_department VARCHAR2(10);
BEGIN

FOR i IN 1.. HTMLDB_APPLICATION.G_F07.COUNT LOOP


SELECT d.department_id
INTO v_department_id
FROM departments d
WHERE d.department = HTMLDB_APPLICATION.G_F15(i);

HTMLDB_APPLICATION.G_F07(i) := v_department_id;

END LOOP;

END;