I need help! TRIGGER PROBLEM.

Question

I have a case where I am checking for conflict do to date/times in table "MAINT".
if an ID that is changed or added in table "SCHEDULE", I need to change the corresponding id in table MAINT, if that change make the id go into conflict, meaning that the start_time and the end_time of the NEW record is in the start and end time of the :OLD record, then I set the conlict flag in the MAINT table to "Y". If the change takes an ID out of conflict, then I set the conflict flag in the MAINT table to "N". Basically my algorithm is:
1. get the OLD.id conflict record
2. get a cursor of all records except the old id conflict record.
3. compare the old id conflict recordd start and end times in the cursor, if there is a conflict in times, then update the record in the cursor and the old_id conlict to 'Y'.
4. get the new_id record (the one that changed).
5. Get the cursor of the new id records except the one that changed.
6. compare the new record to the cursor start and end times.
7. If conflict, update the new record and the one that it has a conflict with.
8. if not a conflict, update the new record.
I hope you can figure out what I am trying to say in a a generic sort of way.

Answer 1

I am sorry...
The trigger that I tried to come up with is:
CREATE OR REPLACE TRIGGER trgupdate_resource_id AFTER
UPDATE OF resource_id ON maintenance_resource_req FOR EACH ROW
DECLARE pragma autonomous_transaction;
BEGIN
UPDATE resource_schedules
SET resource_schedules.resource_id = :NEW.resource_id
WHERE resource_schedules.resource_id = :OLD.resource_id
AND resource_schedules.maintenance_id = :OLD.maintenance_id
AND resource_schedules.step_number = :OLD.step_number;
IF :OLD.resource_id = :NEW.resource_id THEN
IF :OLD.maintenance_id = :NEW.maintenance_id THEN
IF :OLD.step_number = :NEW.step_number THEN
IF((:NEW.scd_start BETWEEN :OLD.scd_start
AND :OLD.scd_end)
AND(:NEW.scd_end BETWEEN :OLD.scd_start
AND :OLD.scd_end)) THEN
:NEW.conflict := 'Y'
ELSE
:NEW.conflict := 'N'
END IF;
END IF;
END IF;
END;
END;
the table structures:
"MAINTENANCE_RESOURCE_REQ"
     "MAINTENANCE_ID" NUMBER NOT NULL ENABLE,
     "STEP_NUMBER" NUMBER NOT NULL ENABLE,
     "RESOURCE_ID" NUMBER,
     "PREVIOUS_RESOURCE_ID" NUMBER,
     "CONFLICT" VARCHAR2(1)
"RESOURCE_SCHEDULES"
"RESOURCE_SCHED_ID" NUMBER NOT NULL ENABLE,
"RESOURCE_ID" NUMBER NOT NULL ENABLE,
"MAINTENANCE_ID" NUMBER,
"STEP_NUMBER" NUMBER,
"SCD_START" DATE,
"SCD_END" DATE
Sample data:
RESOURCE_ID START_TIME END_TIME CONFLICT
1 08:00 09:00 Y
2 08:00 09:00 N
3 10:00 11:00 N
1 08:45 09:15 Y