ORA-20505: Error in DML - Version of data in db has changed

Question

Hello,
Application Express 3.1.0.00.32
I have created a Report and Master Detail in the Sample Application on oracle.application.com. I am receiving an error on my Master Detail Form when clicking the <Previous and Next> buttons. I have viewed other issues like this in the forum but, it looks like everyone is a little different. Can anyone assist me with this error when browsing to the next record(s). Thanks in advance.
ORA-20505: Error in DML: p_rowid=6, p_alt_rowid=CUSTOMER_ID, p_rowid2=, p_alt_rowid2=. ORA-20503: Current version of data in database has changed since user initiated update process. current checksum = "E9A08EDC02A82871E6865DB254B09ED2" application checksum = "39454529513F24BE60C167752BF71750"
I created another Master Detail page and I do not have any errors when scrolling using <> buttons. Here is a process that may be causing my error using the original Master Detail page.
DECLARE
CUSTOMER_ID VARCHAR(20);
BEGIN
SELECT CUSTOMER_ID INTO :P21_CUSTOMER_ID
FROM DEMO_CUSTOMERS
WHERE CUST_FIRST_NAME = :P21_CUST_FIRST_NAME;
-- processing here
EXCEPTION
  -- Catches all 'no data found' errors
   WHEN NO_DATA_FOUND THEN
     DBMS_OUTPUT.PUT_LINE
       ('No Data found for SEARCH on ' || CUSTOMER_ID);
END;Edited by: Charles A on Apr 30, 2009 11:40 AM

Answer 1

Hi Charles,
I've had a look at your page 21.
The problem was that the "Fetch Values 2" process was not conditional and was running in the "On Load - Before Header" process point. This meant that it was being run every time the page was being loaded. This process checks for the CUSTOMER_ID relating to the value in P21_CUST_FIRST_NAME which, because the "Fetch Row..." process hasn't been run at that point (it runs "On Load - After Header"), will always return the same CUSTOMER_ID value from when the page was first loaded. The Next/Previous buttons, however, moved the P21_CUSTOMER_ID forward/back one value (this became apparent when this field was changed from "Hidden and Protected" to "Text"). As a result, the data on the page was for "Albert" but the CUSTOMER_ID value was for whatever record was next/previous to the Albert one. Thus, moving next/previous always caused a mix of the actual data.
I have changed the "Fetch Values 2" process to be conditional on P21_CUSTOMER_ID being NULL. This way, the CUSTOMER_ID value is ONLY found by code when the page is first loaded. Thereafter, it is controlled by the Next/Previous functionality.
Andy