Checkboxes in report to insert or update a value, doesn't do both

Question

I'm going crazy trying to solve this, hopefully someone can help me out. At the moment, I have a credit card table that will contain the information relating to a user-credit card pairing. Banks and such can submit credit cards to users, and the credit card table will be updated, with the column Approved_Flag being set to "N". Now, in another page, I have a report that displays any credit cards that a user may want, along with checkboxes. This report contains any bank submitted cards, or any cards that have been marked "General". Users can decide which ones they would like to keep, and then hit a submit button, which will update the credit card table. Existing records in the table would have the Approved column marked 'Y', new records from the so called "General" cards would be inserted.
The issue is that with the code I've written, it updates any existing records in the credit card table perfectly, but it will not insert any new information. The following is my code for the process that activates when the submit button is hit:
FOR i in 1..APEX_APPLICATION.G_F01.count
LOOP
MERGE INTO ls_credit_cards dest
USING( SELECT apex_application.g_f01(i) credit_card_id,
:F125_USER_ID created_by,
sysdate created_on,
:P54_CARDS card_id,
:P54_USER user_id,
'Y' approved_flag
FROM dual) src
ON( dest.credit_card_id = src.credit_card_id )
WHEN MATCHED
THEN
UPDATE SET dest.approved_flag = src.approved_flag
WHEN NOT MATCHED
THEN
INSERT( credit_card_id,
created_by,
created_on,
card_id,
user_id,
approved_flag )
VALUES( src.credit_card_id,
src.created_by,
src.created_on,
src.card_id,
src.user_id,
src.approved_flag );
END LOOP;
Through some testing, I've found out the the issue is any "General" credit cards will not have a credit card ID assigned to them. By hard coding it, I can get them to insert, but then existing records do not get updated. I've used this code to assign each checkbox in the table a credit_card_id (I think...) so I don't understand why this isn't working.
APEX_ITEM.CHECKBOX(1,credit_card_id) " ",
Could anyone shed some light on how I can do this? I would appreciate it IMMENSELY

Answer 1

A Trigger is just a set of code that runs when certain DML events are applied to a specific table. Here's an example of a simple trigger that assigns a value to a key field when no value is supplied (NULL). Notice that the trigger makes use of another structure - a Sequence - for determining the ID. Sequences are just auto-incrementing values that are very useful for deriving unique values for use in primary key fields, etc.
Here's an example of how to create a sequence using SQL:
CREATE SEQUENCE SEQ_MVR_RATING_SCALE
    MINVALUE 1 INCREMENT BY 1 START WITH 1
/You can also create them directly using the SQL Workshop portion of the APEX console.
Here's an example of how to create a trigger that uses that sequence to populate the key value:
CREATE OR REPLACE TRIGGER  BI_MVR_RATING_SCALE
  before insert on MVR_RATING_SCALE
  for each row
declare
begin
  if :NEW.MVR_RATING is null then
    select SEQ_MVR_RATING_SCALE.nextval into :NEW.MVR_RATING from dual;
  end if;
  if :NEW.ENTERED_BY is null then
    :NEW.ENTERED_BY := FN_GET_USER(nvl(v('APP_USER'),user));
  end if;
  :NEW.ENTERED_ON := SYSDATE;
end;
/Without giving you a complete tutorial on triggers, just note the call to SEQ.nextval. That's what retrieves the next value from the sequence and tells the DB engine to increment the sequence value. The next time it is called, it will then be a different value.