Master-Detail Form - implementing some thing like Post-Query trigger

Question

Hi all,
I am struggling to implement an eqivalent of a post-query trigger in Oracle Forms. Please bear with me as I am trying to explain in detail what the problem is.
Here is my situation.
I have three tables EMP, DEPT and LOCATION. I created a Master/Table pages on EMP and DEPT.
Basic relationships.
Each LOCATION has one or more DEPTs; Each DEPT is at one and only one LOCATION.
Each DEPT has one ore more EMPs; Each EMP is assigned to only and only DEPT.
Not getting too complicated, here are the table layouts:
LOCATION:
ID number(10,0) not null,
NAME varchar2(20) not null
DEPT
ID number(10,0) not null,
NAME varchar2(20) not null,
LOC_ID number (10,0) not null foreign key from LOCATION
EMP
ID number(10,0) not null,
NAME varchar2(20) not null,
DEPT_ID number (10,0) not null foreign key from DEPT
Assume I have all the constraints, BIU triggers, sequences defined properly.
I am using the APEX page wizard to create a Master/Detail Form on DEPT and EMP. The first page is the Master Report on DEPT. I want to display the Location Name on this page also. Because the Master Report allows
you to change the query, I was able to add the Location Name as part of the
query. This was very simple.
Select a.name "Department_Name",
b.name "Location"
from dept a, location b
where a.loc_id = b.id
Moving on, In the Master Detail Form, I would like to get the Location Name as part of the first Region (Dept Region).
In this region, I would like to include the Location Name also. So my first region on the Master Detail form includes:
Dept Id: ________
Dept Name: _______
Location Name: __________
As Region are automatically populated using using a Fetch Row from EMP table (Automated Row Fetch) on an After Header process point, I don't have a way of including the Location as part of query. So I created a Region level Item called Location Name, made it Display only.
In the old SQL*Forms, or Oracle Forms days, I used to use a Post-Query trigger, or Post-Change trigger to fire on the Loc_Id column to populate the Location Name. Simple fetch like:
Select name
into :P80_location_name
from location
where loc_id = :P80_loc_id
However, I am struggling to implement some thing simple like this in APEX. Tried creating a processes, computatations etc, but nothing is working.
I have seen some previous responses to fetching values from a foreign table
using a button or AJAX script, but this should be very basic. What am I
missing here?
Appreciate any insights.
Thanks.
John

Answer 1

Hi John,
I'm not too familiar with the post-query triggers in Oracle Forms, but the use of a List of Values (LOV) on your LOCATION table might do the trick for you. If you create a dynamic LOV based on your LOCATIONS table, it can then be referenced by the LOC_ID item on the Master-Detail page, to display the Location Name. You could try doing the following:
1. Create a new dynamic LOV, LOCATIONS, using a query similar to the following:
select Name d, ID r
from LOCATION
order by 1
2. Edit the "Create" button on the Master report page, and in the "Optional URL Redirect" section set "Request" to CREATE. Click Apply Changes, to save the setting.
3. Edit the LOC_ID item on your Master-Detail page, and set the following:
* in the "Name" region change the "Display As" setting to Select List
* in the "Label" region change the Label to Location Name.
* in the "List of Values" region set the "Named LOV" to LOCATIONS
* in the "Read Only" section, set the condition to Request != Expression 1, and set Expression 1 to CREATE.
Click Apply Changes to save the settings.
When you run the pages now, the Location Name field will appear as Read-Only when editing a selected Master row. The item will appear as a Select List when the user clicks "Create" on the Master page, to create a new Master row.
I hope this helps.
Regards,
Hilary