skip deleting records when a child record is found - plsql

Question

i have a pl/sql procedure to modify/delete records based on a checkbox selection in my Apex application:
delete from s_objectif_operation where id_operation=:p124_id_operation;
for a in (select distinct id from s_objectif
where id in (
SELECT trim(regexp_substr(:P124_S_OBJECTIF, '[^:]+', 1, LEVEL)) str
FROM dual
CONNECT BY instr(:P124_S_OBJECTIF, ':', 1, LEVEL - 1) > 0
))
loop
insert into s_objectif_operation
(id_s_objectif, id_operation)
values
(a.id, :p124_id_operation);
end loop;
for every modification, this procedure deletes all the records and insert the correct ones back so i had to remove the "cascade on delete" option the foreign key constraint to suspend any child record removal but now the procedure is not working.
maybe "raise an exception" can work?

Answer 1

There is no need to delete all the records and re-inserting only the checked ones. That is a brute force approach and it works but it does not capture the real user action.
As an alternative you can just delete/insert the changes. To do that, create an additional page item P124_S_OBJECTIF_OLD and set it to the value P124_S_OBJECTIF with a computation after header (or any pre-rendering processing point after P124_S_OBJECTIF has been initialized). In your pl/sql code use APEX_STRING.SPLIT to process the checkbox values and the MULTISET operator to decide which values have been touched.
Then your pl/sql process code could look like this.
DECLARE
l_objectif_old apex_t_varchar2;
l_objectif_new apex_t_varchar2;
l_objectifs_added apex_t_varchar2;
l_objectifs_removed apex_t_varchar2;
BEGIN
l_objectif_old := apex_string.split(:P124_S_OBJECTIF_OLD,':');
l_objectif_new := apex_string.split(:P124_S_OBJECTIF,':');
l_objectifs_added := l_objectif_new MULTISET EXCEPT l_objectif_old;
l_objectifs_removed := l_objectif_old MULTISET EXCEPT l_objectif_new;
-- add new
FOR i IN 1 .. l_objectifs_added.COUNT LOOP
INSERT INTO s_objectif_operation (id_s_objectif, id_operation)
VALUES (l_objectifs_added(i), :P124_ID_OPERATION);
END LOOP;
-- delete old
FOR i IN 1 .. l_objectifs_removed.COUNT LOOP
BEGIN
DELETE FROM s_objectif_operation
WHERE id = l_objectifs_removed(i);
EXCEPTION WHEN OTHERS THEN
-- this will fire if there are child records. Add your own code.
NULL;
END;
END LOOP;
END;
Note that you might have to tweak the insert and delete statement to match your data structure.