I use postgresql 11.
I think my problem comes from a trigger that doesn't do an update so the next trigger doesn't launch.
I have a table projet with columns : projet_temps_doe, projet_temps_etudes, projet_temps_globale.
The goal is to update each columns depending on other columns values.
The idea is : projet_temps_globale = projet_temps_doe + projet_temps_etudes.
I have a first trigger on projet_temps_doe which works perfectly:
create function temps_globale_doe() returns trigger
language plpgsql
as
$$
begin
new.projet_temps_globale_doe := new.projet_temps_doe_gc_bts + new.projet_temps_doe_gc_nra;
return new;
end;
$$;
CREATE TRIGGER temps_globale_doe
BEFORE UPDATE OF projet_temps_doe_gc_bts, projet_temps_doe_gc_nra
ON public.projet
FOR EACH ROW
EXECUTE PROCEDURE public.temps_globale_doe();
I have a similar trigger on projet_temps_etudes which works perfectly too.
Then the trigger I struggle with on projet_temps_globale :
create trigger maj_temps_globale_projet
before update of projet_temps_doe, projet_temps_etudes on projet
for each row
execute procedure maj_temps_globale_projet();
create or replace function maj_temps_globale_projet()returns trigger
language plpgsql
as
$$
begin
new.projet_temps_globale := new.projet_temps_doe + new.projet_temps_etudes;
raise info 'TEST!!';
return new;
end;
$$;
When projet_temps_doe and/or projet_temps_etudes are updated via triggers my last trigger doesn't launch. However when I manually change projet_temps_doe and/or projet_temps_etudes values the trigger maj_temps_globale_projet is fired.
I want to learn from this, so, if possible, explain to me what I'm doing wrong here, or if my approach is lacking insight.
The doc says
The trigger will only fire if at least one of the listed columns is
mentioned as a target of the UPDATE command.
The column projet_temps_globale_doe is not part of the update command but is rather set in another trigger via new.projet_temps_globale_doe = ... so the trigger on this particular column is not called.
It would be easier to have only one trigger on the entire table that sets the 3 derived values.
Related
I have a table with three columns: id, date and dateDekete
I try to execute an update on the column dateDelete after an update on another column (column date) using a AFTER UPDATE TRIGGER.
The code that I use to create my trigger is the following:
CREATE OR REPLACE FUNCTION update_delete_date_allocation()
RETURNS trigger LANGUAGE plpgsql AS $body$
BEGIN
NEW."dateDelete" := NEW.date + 1;
RETURN NEW;
END;
$body$;
CREATE TRIGGER delete_date_allocation_trg
AFTER INSERT OR UPDATE ON client.client_portfolio_allocation
FOR EACH ROW
EXECUTE PROCEDURE update_delete_date_allocation();
Although the code executes fine with no error message, the latter column that I try to update does not change.
I was wondering if it's possible to do this. AND if so, what should I change in my code?
I am using Postgres 11.5.
you can't change the new record in an AFTER trigger, you need to declare your trigger as a BEFORE trigger:
CREATE TRIGGER delete_date_allocation_trg
BEFORE INSERT OR UPDATE ON client.client_portfolio_allocation
FOR EACH ROW
EXECUTE PROCEDURE update_delete_date_allocation();
I'm trying to create a function + trigger that will update my "modif" attribut to current date when there is an update or insert on my table called "nada".
the code work well but all the rows are affected.I only want the current date on the rows that were updated.
Any idea ?
This is my code so far:
CREATE OR REPLACE FUNCTION public.maj_modif()
RETURNS "trigger" AS
$BODY$
BEGIN
NEW.modif:= (SELECT current_date);
RETURN NEW;
END;
$BODY$
LANGUAGE plpgsql;
DROP TRIGGER IF EXISTS maj_modif ON public.nada;
CREATE TRIGGER maj_modif BEFORE INSERT OR UPDATE ON public.nada
FOR EACH ROW
EXECUTE PROCEDURE public.maj_modif();
If I try the same code without "FOR EACH ROW" in the trigger I get this erreur: « new » is not affected yet (...) The structure of the registration line is not yet determined.
I assume that you only want the trigger to fire if any columns were actually changed.
That can be done with
CREATE TRIGGER maj_modif BEFORE UPDATE ON public.nada
FOR EACH ROW
WHEN OLD <> NEW
EXECUTE PROCEDURE public.maj_modif();
That only works for UPDATE, because on INSERT OLD is not defined. Define the INSERT trigger without the WHEN clause.
I'm migrating an entire database from Firebird to PostgreSQL and it's not rocket science. But I'm having serious trouble with triggers. Specially the Firebird's POSITION argument.
Actually, I'm searching about the POSITION behavior. I need it but in PostgreSQL.
Those are the Triggers in Firebird:
This Trigger needs to be executed first:
/* Trigger: TRG_CFE_ESTOQUE_PROCESSADO */
CREATE OR ALTER TRIGGER TRG_CFE_ESTOQUE_PROCESSADO FOR ITENS_CFE
BEFORE UPDATE POSITION 0
AS
BEGIN
IF(NEW.ITE_QTD <> OLD.ITE_QTD)THEN
BEGIN
NEW.ITE_ESTOQUE_PROCESSADO = 'N';
END
END
And this one needs to be executed after:
/* Trigger: TRG_CFE_ESTOQUE_EXCLUIDO */
CREATE OR ALTER TRIGGER TRG_CFE_ESTOQUE_EXCLUIDO FOR ITENS_CFE
BEFORE DELETE POSITION 1
AS
BEGIN
UPDATE ITENS_CFE
SET ITE_ESTOQUE_PROCESSADO = 'N'
WHERE PRO_CODIGO = OLD.PRO_CODIGO
AND CFE_CODIGO = OLD.CFE_CODIGO;
END
For now, I'm not testing it, just searching for a way to reproduce the expected behavior.
Searching again, I've found something in the PostgreSQL Documentation:
If multiple triggers of the same kind are defined for the same event, they will be fired in alphabetical order by name
And I think it will do the magic.
But is this the best way of doing it?
The standard way I've defined trigger would be like the following:
CREATE OR REPLACE FUNCTION func_table_x_after_insert()
RETURNS TRIGGER
AS $$
BEGIN
INSERT INTO table_y
(id)
VALUES
(NEW.id)
;
RETURN NEW;
END;
$$ LANGUAGE PLPGSQL;
CREATE TRIGGER trig_table_x_after_insert
AFTER INSERT ON table_x
FOR EACH ROW EXECUTE PROCEDURE func_table_x_after_insert();
The function you define can handle multiple steps.
I am trying to create a trigger and procedure to update a last_changed_timestamp column upon UPDATE and INSERT.
I can register the function and trigger just fine, but when I try to update a record I receive the error.
CREATE OR REPLACE FUNCTION update_my_table_last_changed_timestamp()
RETURNS trigger AS
$BODY$
BEGIN
UPDATE my_table SET NEW.last_changed_timestamp = NOW();
RETURN NEW;
END;
$BODY$
LANGUAGE plpgsql;
CREATE TRIGGER trigger_update_my_table_last_changed_timestamp
BEFORE UPDATE
ON my_table
FOR EACH ROW
EXECUTE PROCEDURE update_my_table_last_changed_timestamp();
column "new" of relation "my_table" does not exist
I also do not fully understand how update_my_table_last_changed_timestamp knows which row it's suppose to update, nor if there were parameters passed to it, how the I would get those variables from the trigger to the procedure.
Modify the NEW record, there is no need to update.
BEGIN
NEW.last_changed_timestamp = NOW();
RETURN NEW;
END;
Read in the documentation: Overview of Trigger Behavior
If you still want to access a (other )table in the update trigger.
You can add to beginning of your trigger body the following:
EXECUTE format('SET search_path TO %I', TG_TABLE_SCHEMA);
For some reason with the update trigger it can happen that you're not on the correct search_path (i believe some old psql version have this)
In Postgresql I can have two kinds of triggers: FOR EACH ROW and FOR EACH STATEMENT. If I do a FOR EACH ROW trigger, I can add a WHERE clause something like OLD.* != NEW.* so it only fires if something has actually changed. Is there any way to do something similar with STATEMENT level triggers? I know I can't do the same thing since OLD and NEW aren't available, but I was thinking perhaps there might be a way to check the number of rows changed from within my function itself or the like.
Usage case: I am using the postgresql NOTIFY system to notify my app when data changes. Ideally, the app would get a single notification each time one or more records changes, and not get notified at all if data stays the same (even if an UPDATE was run). With a basic AFTER UPDATE FOR EACH STATEMENT trigger, I am getting notified every time an update statement runs - even if it doesn't actually change anything.
You should create two triggers: before update for each row and after update for each statement.
The first trigger checks if the table is being updated and sets a flag if so.
The second trigger checks the flag and performs notify if it was set.
You can use a custom configuration parameter as the flag (e.g. flags.the_table).
The solution is simple and safe, as the parameter is local in the current session.
create or replace function before_each_row_on_the_table()
returns trigger language plpgsql
as $$
begin
if new <> old then
set flags.the_table to 'on';
end if;
return new;
end $$;
create or replace function after_each_statement_on_the_table()
returns trigger language plpgsql
as $$
begin
if current_setting('flags.the_table', true) = 'on' then
notify your_channel, 'the_table was updated';
set flags.the_table to 'off';
end if;
return null;
end $$;
create trigger before_each_row_on_the_table
before update on the_table
for each row execute procedure before_each_row_on_the_table();
create trigger after_each_statement_on_the_table
after update on the_table
for each statement execute procedure after_each_statement_on_the_table();
The function current_setting() with two arguments is available in Postgres 9.6 or later.