I would like to write a trigger with FOR EACH STATEMENT. This trigger will listen multiple events and I don't use transition tables in my trigger.
So, can I get the change data with the code below?
CREATE OR REPLACE FUNCTION on_delete_update_employee_ref()
RETURNS trigger
LANGUAGE plpgsql
AS $$
BEGIN
DELETE FROM employee_ref
WHERE id in (SELECT ins_upd_del.id
FROM TG_TABLE_NAME ins_upd_del
WHERE ins_upd_del.employee_type = 'new');
RETURN NULL;
END;
$$;
DROP TRIGGER IF EXISTS on_delete_update_employee_ref ON employee;
CREATE TRIGGER on_delete_update_employee_ref
AFTER INSERT OR UPDATE OR DELETE ON employee
FOR EACH STATEMENT
EXECUTE FUNCTION on_delete_update_employee_ref();
Related
I am looking for an elegant solution to this situation:
I have created a trigger function that updates the table supply with the sum of some detail rows, whenever a row is inserted or updated on warehouse_supplies.
PostgreSQL insert or update syntax allowed me to share the same function sync_supply_stock() for the insert and update conditions.
However, when I try to wire the after delete condition to the function it cannot be reused (although it is logically valid), for the returning object must be old instead of new.
-- The function I want to use for the 3 conditions (insert, update, delete)
create or replace function sync_supply_stock ()
returns trigger
as $$
begin
-- update the supply whose stock just changed in warehouse_supply with
-- the sum its stocks on all the warehouses.
update supply
set stock = (select sum(stock) from warehouse_supplies where supply_id = new.supply_id)
where supply_id = new.supply_id;
return new;
end;
$$ language plpgsql;
-- The (probably) unnecessary copy of the previous function, this time returning old.
create or replace function sync_supply_stock2 ()
returns trigger
as $$
begin
-- update the supply whose stock just changed in warehouse_supply with
-- the sum its stocks on all the warehouses.
update supply
set stock = (select sum(stock) from warehouse_supplies where supply_id = old.supply_id)
where supply_id = old.supply_id;
return old;
end;
$$ language plpgsql;
-- The after insert/update trigger
create trigger on_warehouse_supplies__after_upsert after insert or update
on warehouse_supplies for each row
execute procedure sync_supply_stock ();
-- The after delete trigger
create trigger on_warehouse_supplies__after_delete after delete
on warehouse_supplies for each row
execute procedure sync_supply_stock2 ();
Am I missing something or is there any fixing to duplicating sync_supply_stock2() as sync_supply_stock2()?
EDIT
For the benefit of future readers, following #bergi answer and discusion, this is a possible factorized solution
create or replace function sync_supply_stock ()
returns trigger
as $$
declare
_supply_id int;
begin
-- read the supply_id column from `new` on insert/update conditions and from `old` on delete conditions
_supply_id = coalesce(new.supply_id, old.supply_id);
-- update the supply whose stock just changed in of_warehouse_supply with
-- the sum its stocks on all the warehouses.
update of_supply
set stock = (select sum(stock) from of_warehouse_supplies where supply_id = _supply_id)
where supply_id = _supply_id;
-- returns `new` on insert/update conditions and `old` on delete conditions
return coalesce(new, old);
end;
$$ language plpgsql;
create trigger on_warehouse_supplies__after_upsert after insert or update
on of_warehouse_supplies for each row
execute procedure sync_supply_stock ();
create trigger on_warehouse_supplies__after_delete after delete
on of_warehouse_supplies for each row
execute procedure sync_supply_stock ();
for the returning object must be old instead of new.
No. The return value is only relevant for BEFORE ROW or INSTEAD OF triggers. From the docs: "The return value of a row-level trigger fired AFTER or a statement-level trigger fired BEFORE or AFTER is always ignored; it might as well be null".
So you can just make your sync_supply_stock trigger function RETURN NULL and it can be used on all operations.
I have this table for which one of the columns is to be filled with values from other columns of the same table (these other columns represent a taxonomic hierarchy whose lowest level I wish to store in this other column).
To achieve this I implemented the following trigger:
CREATE OR REPLACE FUNCTION get_taxon()
RETURNS TRIGGER LANGUAGE plpgsql AS
$BODY$
BEGIN
UPDATE taxon SET taxon = coalesce(subespecie, especie, genero, subfamilia, familia, infraordem, subordem, ordem, superordem, subclasse, classe, subphylum, phylum, reino )
WHERE taxon IS NULL;
RETURN NEW;
END
$BODY$
VOLATILE;
CREATE TRIGGER update_taxon
AFTER INSERT OR UPDATE ON taxon
FOR EACH STATEMENT
WHEN (pg_trigger_depth() = 0) -- Prevent recursive trigger calls
EXECUTE PROCEDURE get_taxon();
When I insert a new record the trigger works as expected, but if I update an existing record, nothing happens - the trigger just ignores UPDATE operations and I don't know why.
Can anyone shed some light on this please?
After your statement trigger first fired all records in the table should have their taxon field updated with the best available information. When you update a record you may want to update the taxon value, but you are better off with a BEFORE INSERT OR UPDATE FOR EACH ROW trigger. The only new data is contained in the row for which the trigger fires, of course. So try this:
CREATE OR REPLACE FUNCTION get_taxon()
RETURNS TRIGGER LANGUAGE plpgsql AS
$BODY$
BEGIN
NEW.taxon := coalesce(NEW.subespecie, NEW.especie, NEW.genero, NEW.subfamilia,
NEW.familia, NEW.infraordem, NEW.subordem, NEW.ordem, NEW.superordem,
NEW.subclasse, NEW.classe, NEW.subphylum, NEW.phylum, NEW.reino);
RETURN NEW;
END;
$BODY$ VOLATILE;
CREATE TRIGGER update_taxon
BEFORE INSERT OR UPDATE ON taxon
FOR EACH ROW EXECUTE PROCEDURE get_taxon();
How to apply an update after an insert or update in POSTGRESQL; I have got a table which has a field lastupdate; I want that field to be set up whenever the row is updated or when it was inserted.
I tried this trigger, but It is not working! HELP!!
CREATE OR REPLACE FUNCTION fn_update_profile()
RETURNS TRIGGER AS $update_profile$
BEGIN
IF (TG_OP = 'INSERT' OR TG_OP = 'UPDATE' ) THEN
UPDATE profile SET lastupdate=now() where oid=OLD.oid;
RETURN NULL;
ELSEIF (TG_OP = 'DELETE') THEN
RETURN NULL;
END IF;
RETURN NULL; -- result is ignored since this is an AFTER trigger
END;
$update_profile$ LANGUAGE plpgsql;
Your trigger function can be a lot easier than you had. Keep in mind that PG will do the update or the insert on the original table, you only have to deal with keeping the profile table up-to-date:
CREATE OR REPLACE FUNCTION fn_update_profile()
RETURNS TRIGGER AS $update_profile$
BEGIN
UPDATE profile SET lastupdate = now() WHERE oid = NEW.oid;
RETURN NEW;
END;
$update_profile$ LANGUAGE plpgsql;
The INSERT and UPDATE trigger functions both use the NEW parameter; the INSERT trigger function does not have the OLD parameter. You should always return NEW from the trigger function if successful (or OLD from a DELETE trigger), even if it is an AFTER INSERT OR UPDATE trigger; the whole operation will be rolled back if NULL is returned. If you then define the actual trigger to fire after the insert or update, you should be good:
CREATE TRIGGER tr_update_profile
AFTER INSERT OR UPDATE ON my_table
FOR EACH ROW EXECUTE PROCEDURE fn_update_profile();
I want to create a trigger so that whenever I make a change (Update or Delete) it should copy the old data to a new table (with same template).
I tried this code:
create table restrictions(ID int,name text);
insert into restrictions values(122,'suresh');
select * from restrictions;
create table restrictions_deleted(ID int,name text);// this is my duplicate table for keeping information of all updations.
CREATE OR REPLACE FUNCTION moveDeleted() RETURNS trigger AS $$
BEGIN
INSERT INTO restrictions_deleted VALUES(OLD.ID, OLD.name);
RETURN OLD;
END;
$$ LANGUAGE plpgsql;
CREATE OR REPLACE TRIGGER moveDeleted
BEFORE DELETE ON restrictions
FOR EACH ROW
EXECUTE PROCEDURE moveDeleted();
delete from restrictions where ID=122;
select * from restrictions_deleted;
This code is capable of recording all the deleted data into duplicate table. But I want to do same for updates also.
Any suggestion, any idea?
First - in a trigger function you need to RETURN NEW; instead of RETURN OLD;.
Second - change the trigger to BEFORE DELETE OR UPDATE.
Last - it is better to have AFTER DELETE OR UPDATE for a logging trigger. This way it wont do useless work, when the change is rolled back.
BTW here is a good example of logging/audit trigger.
UPDATE:
The function will look like:
CREATE OR REPLACE FUNCTION moveDeleted() RETURNS trigger AS $$
BEGIN
IF (TG_OP = 'UPDATE') THEN
INSERT INTO restrictions_deleted VALUES(OLD.ID, OLD.name);
RETURN NEW;
ELSIF (TG_OP = 'DELETE') THEN
INSERT INTO restrictions_deleted VALUES(OLD.ID, OLD.name);
RETURN OLD;
END IF;
END;
$$ LANGUAGE plpgsql;
I need help in Postgres triggers.
I have table with 2 columns:
sold boolean;
id_shop int;
It stores if item is sold, or at which shop its located at.
I need a trigger, if I change the "sold" to true, then it also changes the id_shop to NULL (It can't be in shop if sold...)
I tried different ways, but it doesn't work or gives an error on update cmd...
create or replace function pardota_masina_veikals() RETURNS trigger AS $pardota_masina$
begin
IF NEW.sold=true THEN
update masinas
SET id_shop=null WHERE id=NEW.id;
END IF;
RETURN NEW;
END;
$pardota_masina$ LANGUAGE plpgsql;
CREATE TRIGGER pardota_masina_nevar_but_veikala
AFTER INSERT OR UPDATE ON masinas FOR EACH ROW EXECUTE PROCEDURE pardota_masina_veikals();
First of all you need a before trigger if you want to change a value of the row being updated (or inserted)
Secondly you don't need to "update" the table, just assign the new value to the NEW row:
create or replace function pardota_masina_veikals()
RETURNS trigger
AS
$pardota_masina$
begin
IF NEW.sold=true THEN
NEW.id_shop = NULL;
END IF;
RETURN NEW;
END;
$pardota_masina$
LANGUAGE plpgsql;
CREATE TRIGGER pardota_masina_nevar_but_veikala
BEFORE INSERT OR UPDATE ON masinas
FOR EACH ROW EXECUTE PROCEDURE pardota_masina_veikals();