I try to create a generic trigger function which is used to update "updated_at" column value from table when it is updating it.
My trigger function:
CREATE OR REPLACE FUNCTION update_created_at_column() RETURNS TRIGGER AS $$
BEGIN
NEW.created_at = NOW();
return NEW;
END;
$$ LANGUAGE plpgsql;
Trigger assignment to the concerned table:
CREATE TRIGGER type_trigger_updated_at_column AFTER UPDATE ON "type"
FOR EACH ROW EXECUTE FUNCTION update_created_at_column();
Currently, I have no error when I execute them, but when I update a field on my table, "created_at" column is not updated.
The value can be changed only in BEFORE triggers.
The Postgres knows more types of triggers - BEFORE triggers are executed before the value is stored to table, AFTER triggers are executed when the value is visible in table. You should to use BEFORE trigger - you need to modify row before it is stored to the table.
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 have the following functions and trigger with sequence setup:
I want to create a function and trigger that anytime I add a new row to STRATEGY_SITES table, the 'SITE_NUM' field will have the new sequential number from SITENUM_SEQ. Schema name is gismgr.
I am getting the following error:Underlying DBMS error[Error:control reached end of trigger procedure without return Context: PL/pgSQL function process_sites_edit()(gismgr.strategy_sites)::SQLSTATE=2F005][gismgr.startegy_sites]
CREATE OR REPLACE FUNCTION process_sites_edit() RETURNS TRIGGER AS $SITE_EDIT_TRIGGER$
begin
new.SITE_NUM := nextval('gismgr.SITENUM_SEQ');
end;
$SITE_EDIT_TRIGGER$ LANGUAGE 'plpgsql';
create TRIGGER SITE_EDIT_TRIGGER
before insert or update on STRATEGY_SITES for each row
EXECUTE PROCEDURE process_strategy_sites_edit();
CREATE SEQUENCE gismgr."SITENUM_SEQ" owned by gismgr.strategy_Sites.site_num
INCREMENT 1
START 19080
MINVALUE 19080
MAXVALUE 9999999999999999
CACHE 20;
This seems to be an ORACLEism which is unnecessary in Postgres. Assuming your table already exsists then just
alter table *table_name* alter column site_num default nextval('gismgr.SITENUM_SEQ')
Also make sure the insert does not mention the site_num column. If you feel you must continue with the trigger approach the your trigger function needs to specify the return value.
CREATE OR REPLACE FUNCTION process_sites_edit()
RETURNS TRIGGER AS $SITE_EDIT_TRIGGER$
begin
new.SITE_NUM := nextval('gismgr.SITENUM_SEQ');
return new;
end;
$SITE_EDIT_TRIGGER$ LANGUAGE 'plpgsql';
I would also suggest you do not want to fire the trigger on updates. That will change the site number on any/every update of a given row Are there FK referencing it - they will not be updated the update would fail. Further the procedure executed must match the function name:
create TRIGGER SITE_EDIT_TRIGGER
before insert on STRATEGY_SITES for each row
EXECUTE PROCEDURE process_sites_edit();
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 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)
I have a table called 'custom_manual_edit' with columns 'name', 'builder' and 'flag' in which there is no column with primary key.I have written a trigger when user update any change in builder column and that trigger will invoke a function that should update a flag column value to 10 for record for which builder value is changed
below is my trigger
CREATE TRIGGER builder_update_trigger_manual_custom_edits
AFTER UPDATE
ON edmonton.custom_manual_edit
FOR EACH ROW
WHEN (((old.builder)::text IS DISTINCT FROM (new.builder)::text))
EXECUTE PROCEDURE
edmonton.automated_builder_update_trigger_manual_custom_edits();
and my function
CREATE OR REPLACE FUNCTION
edmonton.automated_builder_update_trigger_manual_custom_edits()
RETURNS trigger AS
$BODY$
DECLARE
e record;
BEGIN
IF NEW.builder <> OLD.builder THEN
EXECUTE FORMAT('UPDATE edmonton.custom_manual_edit set builder_edit_flag = 10;
END IF;
RETURN NEW;
END
$BODY$
LANGUAGE plpgsql VOLATILE
COST 100;
I know this will update entire table flag column to 10 but how to update flag value for records for which builder value is changed.
Please check the documentation: 36.1. Overview of Trigger Behavior
Trigger functions invoked by per-statement triggers should always
return NULL. Trigger functions invoked by per-row triggers can return
a table row (a value of type HeapTuple) to the calling executor, if
they choose. A row-level trigger fired before an operation has the
following choices:
It can return NULL to skip the operation for the current row. This
instructs the executor to not perform the row-level operation that
invoked the trigger (the insertion, modification, or deletion of a
particular table row).
For row-level INSERT and UPDATE triggers only, the returned row
becomes the row that will be inserted or will replace the row being
updated. This allows the trigger function to modify the row being
inserted or updated.
A row-level BEFORE trigger that does not intend to cause either of
these behaviors must be careful to return as its result the same row
that was passed in (that is, the NEW row for INSERT and UPDATE
triggers, the OLD row for DELETE triggers).
According to the above you must:
declare the trigger as BEFORE UPDATE, not AFTER UPDATE
changebuilder_edit_flag column value directly in NEW row instead of firing UPDATE statement
CREATE TRIGGER builder_update_trigger_manual_custom_edits
BEFORE UPDATE
ON edmonton.custom_manual_edit
FOR EACH ROW
.....
.....
CREATE OR REPLACE FUNCTION
edmonton.automated_builder_update_trigger_manual_custom_edits()
.....
.....
BEGIN
IF NEW.builder <> OLD.builder THEN
NEW.builder_edit_flag = 10;
END IF;
RETURN NEW;
.....
.....