Business rules to implement - BEST way - triggers and mutating table

Question

I have the following table where it has Foreign Key defined on itself(self reference for parent_id column which can be null or valid site_id)
create table test_virtual_site
site_id number CONSTRAINT site_id_pk primary key,
parent_id number CONSTRAINT parent_site_id_unq UNIQUE ,
closed_date date default NULL ,
CONSTRAINT check_self_ref CHECK(parent_site_id <> site_id), --avoid self refernce
CONSTRAINT check_valid_site foreign key(parent_site_id) references test_virtual_site(site_id)
I have the following business rules to implement and my problem is related to their implementation
1)     A check should be made that Site_id specified as parent_id should not be a child of any other store (parent should have its parent_id column as NULL)
Site_id Parent_id
1
2 1
3 2 =>NOT VALID 2 is a child of another store
2)     Parent is not closed
Site_id Parent_id Closed_date
1 10-May-2005
3     1 =>NOT VALID 1 is a closed
3)
when parent store is closed - updated so at closed_date is not null
Want to set the parent_id as NULL for the child store.
OR
SET the closed_date for child store too same as the parent_store.
Example
Site_id Parent_id Closed_date
1     
1 2
Update test_virtual_site
SET closed_date = sysdate
Where site_id = 1 ;
Through Trigger
Site_id Parent_id Closed_date
1     22-Mar-06
1 2 22-Mar-06
OR
Site_id Parent_id Closed_date
1     22-Mar-06
1
When I am trying to do the above mentioned through constraints I am running into mutating trigger problem. Can you please guide me what is the best way to handle the above-mentioned scenarios.
I am aware that I can avoid the 3rd problem using the following
-- - Initialize an array in the before statement trigger.
-- - Add the processed rowid to the array in the after row
-- trigger.
-- - In the after statement trigger: get each rowid from the
-- array and process it. When all rowids are processed, clear
-- the array.
BUT for 1 and 2 I need to look at the parent specified , the parent exists in the same table BUT I can not perform the lookup from the BEFORE INSERT ROW LEVEL trigger but I want to ensure at the row level , so if the parent store is closed or parent specifed itself is a child(not permissible) I want to rollback the insert – RAISE_APPLICATION_ERROR.
Can you please guide me what is the best way to handle the above mentioned conditions .

Answer 1

I have the following table where it has Foreign Key defined on itself(self reference for parent_id column which can be null or valid site_id)
create table test_virtual_site
site_id number CONSTRAINT site_id_pk primary key,
parent_id number CONSTRAINT parent_site_id_unq UNIQUE ,
closed_date date default NULL ,
CONSTRAINT check_self_ref CHECK(parent_site_id <> site_id), --avoid self refernce
CONSTRAINT check_valid_site foreign key(parent_site_id) references test_virtual_site(site_id)
I have the following business rules to implement and my problem is related to their implementation
1)     A check should be made that Site_id specified as parent_id should not be a child of any other store (parent should have its parent_id column as NULL)
Site_id Parent_id
1
2 1
3 2 =>NOT VALID 2 is a child of another store
2)     Parent is not closed
Site_id Parent_id Closed_date
1 10-May-2005
3     1 =>NOT VALID 1 is a closed
3)
when parent store is closed - updated so at closed_date is not null
Want to set the parent_id as NULL for the child store.
OR
SET the closed_date for child store too same as the parent_store.
Example
Site_id Parent_id Closed_date
1     
1 2
Update test_virtual_site
SET closed_date = sysdate
Where site_id = 1 ;
Through Trigger
Site_id Parent_id Closed_date
1     22-Mar-06
1 2 22-Mar-06
OR
Site_id Parent_id Closed_date
1     22-Mar-06
1
When I am trying to do the above mentioned through constraints I am running into mutating trigger problem. Can you please guide me what is the best way to handle the above-mentioned scenarios.
I am aware that I can avoid the 3rd problem using the following
-- - Initialize an array in the before statement trigger.
-- - Add the processed rowid to the array in the after row
-- trigger.
-- - In the after statement trigger: get each rowid from the
-- array and process it. When all rowids are processed, clear
-- the array.
BUT for 1 and 2 I need to look at the parent specified , the parent exists in the same table BUT I can not perform the lookup from the BEFORE INSERT ROW LEVEL trigger but I want to ensure at the row level , so if the parent store is closed or parent specifed itself is a child(not permissible) I want to rollback the insert – RAISE_APPLICATION_ERROR.
Can you please guide me what is the best way to handle the above mentioned conditions .