Here is my trigger function
CREATE OR REPLACE FUNCTION test_table_insert()
RETURNS TRIGGER
AS $$
BEGIN
IF NEW.id IS NULL THEN
RAISE EXCEPTION 'id is null';
END IF;
UPDATE e_sub_agreement SET ro_id = NEW.id WHERE id = NEW.id;
RETURN NEW;
END;
$$
LANGUAGE plpgsql;
CREATE TRIGGER test_table_insert AFTER INSERT ON e_sub_agreement FOR EACH ROW EXECUTE PROCEDURE test_table_insert();
The problem is that it doesn't update table e_sub_agreement. I checked NEW value and everything is good. It returns with the new id. If I change where statement id = "some existing id in table", then it works. It changes ro_id to the new id. How is it possible? My guess is that data has not been inserted into table and trigger function can't find row with the given id. But it's not how trigger's after insert function works. What's the magic?
An AFTER trigger can not change anything. Running an additional UPDATE is also quite inefficient. Change this to a BEFORE trigger and assign the value you want:
CREATE OR REPLACE FUNCTION test_table_insert()
RETURNS TRIGGER
AS $$
BEGIN
IF NEW.id IS NULL THEN
RAISE EXCEPTION 'id is null';
END IF;
NEW.ro_id := NEW.id;
RETURN NEW;
END;
$$
LANGUAGE plpgsql;
CREATE TRIGGER test_table_insert
BEFORE INSERT ON e_sub_agreement
FOR EACH ROW EXECUTE PROCEDURE test_table_insert();
Note that the NOT NULL check is better done by defining the column as NOT NULL.
Related
I wan't to add a trigger in a PostgreSQL database. This trigger is used to concatenate values of 2 columns to update a 3rd one. I wan't to run it when a row is inserted or updated in the table.
Table
CREATE TABLE IF NOT EXISTS FILE(ID INT NOT NULL PRIMARY KEY, FOLDER TEXT, NAME TEXT, URL TEXT);
Function
CREATE OR REPLACE FUNCTION LINK() RETURNS trigger AS
$$
BEGIN
IF (TG_OP = 'UPDATE') THEN
UPDATE FILE
SET URL = CONCAT(FOLDER, NAME)
WHERE ID = OLD.ID;
ELSIF (TG_OP = 'INSERT') THEN
UPDATE FILE
SET URL = CONCAT(FOLDER, NAME)
WHERE ID = NEW.ID;
END IF;
RETURN NULL;
END
$$
LANGUAGE PLPGSQL;
Trigger
CREATE TRIGGER TRIGGER_LINK
BEFORE INSERT OR UPDATE
ON FILE
FOR EACH ROW
EXECUTE PROCEDURE LINK();
When I insert a value in table like
INSERT INTO FILE VALUES (1, 'C:\', 'doc.pdf');
I have an error message list index out of range because ID number is not yet created and UPDATE query on INSERT can't execute. But if I make an AFTER UPDATE it will run infinitely.
How to run a trigger function on INSERT or UPDATE with a WHERE clause on ID to target only inserted or updated row ? I'm using PostgreSQL 10.14.
Don't use UPDATE to do that. Just assign the value. Also, a BEFORE trigger should not return null because that will abort the operation.
CREATE OR REPLACE FUNCTION LINK() RETURNS trigger AS
$$
BEGIN
new.url := CONCAT(new.FOLDER, new.NAME);
RETURN new; --<< important!
END
$$
LANGUAGE PLPGSQL;
I'm trying to mark a boolean column on a different table to true upon the insertion of a matching record.
Here's what I've got:
CREATE or replace FUNCTION mark_as_sold() RETURNS trigger AS
$BODY$
BEGIN
UPDATE listing
set listing.sold = true;
WHERE listing.id = NEW.listing_id;
RETURN NEW;
END
$BODY$
LANGUAGE plpgsql;
CREATE TRIGGER update_child_after_update
AFTER INSERT
ON transaction
FOR EACH ROW
EXECUTE PROCEDURE mark_as_sold();
When I create a record on the transaction table, nothing happens. I'm stumped. Any help is greatly appreciated.
I figured it out. I was messing up my relations. Here's the proper code:
CREATE OR REPLACE FUNCTION mark_as_sold()
RETURNS TRIGGER
AS $$
BEGIN
UPDATE listing
set sold = true
WHERE listing.id = NEW.listing_id;
RETURN NEW;
RETURN NEW;
END;
$$
LANGUAGE plpgsql;
CREATE TRIGGER test_trigger BEFORE INSERT OR UPDATE
ON "transaction"
FOR EACH ROW EXECUTE PROCEDURE mark_as_sold();
My before update trigger throws an error on updating single row in table company.
ERROR: relation "new" does not exist, row 7.
Trigger and trigger function code:
CREATE OR REPLACE FUNCTION public.check_company_transitivity()
RETURNS trigger
AS $$
DECLARE
cmp uuid;
head_company uuid;
audited_company uuid;
BEGIN
audited_company := (select NEW.id from NEW);
cmp:=audited_company;
head_company:='*';
while head_company is not null loop
head_company:=(select head_company from company where id=cmp);
if audited_company=head_company then
raise exception 'transitive closure';
else
cmp=head_company;
end if;
end loop;
return new;
END;
$$ LANGUAGE plpgsql;
create trigger check_company_transitivity
before update
on
public.company for each row execute procedure check_company_transitivity();
I can’t understand what the problem is, I would be appreciate for any help.
You can use the values from NEW directly
audited_company := NEW.id;
I want to update the record of a particular user only. But the update trigger fires for all the users.
CREATE OR REPLACE FUNCTION replace_empty_username_with_null() RETURNS TRIGGER
LANGUAGE plpgsql AS
BEGIN
UPDATE user_temp
SET username=null
WHERE NEW.id = OLD.id and NEW.username = '';
RETURN NEW;
END
CREATE TRIGGER replace_empty_username
AFTER UPDATE OF username ON user_temp
FOR EACH ROW
WHEN (NEW.username = '' AND OLD.id = NEW.id)
EXECUTE PROCEDURE replace_empty_username_with_null();
The expression NEW.id = OLD.id makes sense in the WHEN clause of the trigger ("ID did not change and is not null"). But it makes no sense in the body of the trigger function, where it burns down to TRUE. Also, to only affect the row which is being updated, just use a BEFORE trigger instead:
CREATE OR REPLACE FUNCTION replace_empty_username_with_null()
RETURNS TRIGGER LANGUAGE plpgsql AS
$func$
BEGIN
NEW.username = null; -- !
RETURN NEW;
END
$func$
CREATE TRIGGER replace_empty_username
BEFORE UPDATE OF username ON user_temp -- !
FOR EACH ROW
WHEN (NEW.username = '' AND OLD.id = NEW.id)
EXECUTE PROCEDURE replace_empty_username_with_null();
Related:
PostgreSQL Update trigger
I need help with my trigger. For example i have Query like this
INSERT INTO test(id_users,id_type,id_color) VALUES(1,3,4);
in my data base i have table with name: test
ghost, id, id_users, id_type, id_color
and i need before insert or update to check
Create trigger
Begin
select id from test where ghost = false and id_users = 26 and id_type = 3
if NO execute INSERT
if YEST exit with no action
END
How can i creat this trigger ?
There are two ways, depending on how you want to manage the problem.
If you wish to silence it, use a before trigger and return null:
create function ignore_invalid_row() returns trigger as $$
begin
if not exists(
select 1
from test
where not ghost
and id_users = new.id_users
and id_type = new.id_type
)
then
return null;
end if;
return new;
end;
$$ language plpgsql;
create trigger ignore_invalid_row_tg before insert on test
for each row execute procedure ignore_invalid_row();
If you wish to raise it, use a constraint trigger and raise an exception:
create function reject_invalid_row() returns trigger as $$
begin
if not exists(
select 1
from test
where not ghost
and id_users = new.id_users
and id_type = new.id_type
)
then
raise exception 'message';
end if;
return null;
end;
$$ language plpgsql;
create constraint trigger reject_invalid_row_tg after insert on test
for each row execute procedure reject_invalid_row();
http://www.postgresql.org/docs/current/static/sql-createtrigger.html
First, you need to create a trigger function and then the trigger, based on it:
CREATE OR REPLACE FUNCTION my_trigger_function() RETURNS TRIGGER AS $BODY$ BEGIN
IF EXISTS (SELECT id FROM test WHERE ghost = false AND id_users = 26 AND id_type = 3) THEN
return NEW;
ELSE
return NULL;
END IF; END; $BODY$ LANGUAGE 'plpgsql';
Then, you create trigger based on this function:
CREATE TRIGGER t_my_trigger BEFORE INSERT ON test FOR EACH ROW EXECUTE PROCEDURE my_trigger_function();
For more on triggers, see postgres docs.