I have a trigger function that copy row of unique values to another table on update or insert that ALMOST work.
The trigger should only insert a new row to the sample table if the number don't exist in it before. Atm. it insert a new row to the sample table with the value NULL if the number already exist in the table. I dont want it to do anything if maintbl.number = sample.nb_main
EDIT: sample table and sample data
CREATE TABLE schema.main(
sid SERIAL NOT NULL,
number INTEGER,
CONSTRAINT sid_pk PRIMARY KEY (sid)
)
CREATE TABLE schema.sample(
gid SERIAL NOT NULL,
nb_main INTEGER,
CONSTRAINT gid_pk PRIMARY KEY (gid)
Example and desired result
schema.main schema.sample
number nb_main
234233 234233
234234 555555
234234
555555
555555
CREATE OR REPLACE FUNCTION schema.update_number()
RETURNS trigger AS
$BODY$
BEGIN
INSERT INTO schema.sample(
nb_main)
SELECT DISTINCT(maintbl.number)
FROM schema.maintbl
WHERE NOT EXISTS (
SELECT nb_main FROM schema.sample WHERE maintbl.number = sample.nb_main);
RETURN NEW;
END;
$BODY$
LANGUAGE plpgsql VOLATILE
COST 100;
ALTER FUNCTION schema.update_number()
OWNER TO postgres;
CREATE TRIGGER update_number
AFTER INSERT OR UPDATE
ON schema.maintbl
FOR EACH ROW
EXECUTE PROCEDURE schema.update_number();
I just found out that my select query is probably wrong, if I run SELECT query by itself it return one row 'NULL' but i should not?
SELECT DISTINCT(maintbl.number)
FROM schema.maintbl
WHERE NOT EXISTS (
SELECT nb_main FROM schema.sample WHERE maintbl.number = sample.nb_main);
Any good advice?
Best
If I understood correctly, you wish to append to schema.sample a number that has been inserted or updated in schema.maintbl, right?
CREATE OR REPLACE FUNCTION schema.update_number()
RETURNS trigger AS
$BODY$
BEGIN
IF (SELECT COUNT(*) FROM schema.sample WHERE number = NEW.number) = 0 THEN
INSERT INTO schema.sample(nb_main) VALUES (NEW.number);
END IF;
RETURN NEW;
END;
$BODY$
LANGUAGE plpgsql VOLATILE;
Related
I am working with the sample DVD_Rental database. I have to create a trigger on my category_performance_details table that will create a summary table every time data is added to the detail table.
These are the queries I am using to setup my tables:
DROP TABLE IF EXISTS category_performance_summary;
CREATE TABLE category_performance_summary (
genre VARCHAR(25),
total_sales numeric
);
DROP TABLE IF EXISTS category_performance_details;
CREATE TABLE if not exists category_performance_details (
category_id Int,
category_name VARCHAR(25),
film_id Int,
film_title VARCHAR(255),
film_rental_rate numeric(4,2),
inventory_id Int,
payment_id Int,
payment_amount numeric(4,2),
rental_id Int,
rental_date Timestamp
);
I want to update the summary table after every insert statement with a trigger so that it provides a summary of the total sales per category. Basically, the summary table should be the same result as:
SELECT category_name, SUM(payment_amount) FROM category_performance_details
GROUP BY category_name;
This is my procedure and trigger. For some reason, I am getting a syntax error at or near "CREATE TRIGGER". Am I approaching this trigger correctly? What is wrong with my syntax?
CREATE OR REPLACE FUNCTION update_summary_table()
RETURNS TRIGGER
LANGUAGE PLPGSQL
AS
$$
BEGIN
TRUNCATE TABLE category_performance_summary;
INSERT INTO category_performance_summary (genre, total_sales)
SELECT category_name, SUM(payment_amount)
FROM category_performance_details
GROUP BY category_name;
RETURN NEW;
END;
$$
CREATE TRIGGER update_summary
AFTER INSERT
ON category_performance_summary
FOR EACH STATEMENT
EXECUTE PROCEDURE update_summary_table();
You can also simply increment or decrement the total_sales in the trigger function.
In any case you have to use the NEW (resp. OLD) key word in order to refer to the values that are inserted/updated (resp. deleted) in table category_performance_summary :
CREATE OR REPLACE FUNCTION increment_summary_table()
RETURNS TRIGGER
LANGUAGE PLPGSQL
AS
$$
BEGIN
INSERT INTO category_performance_summary (genre, total_sales)
VALUES (NEW.category_name, 1)
ON CONFLICT (genre) DO UPDATE
SET total_sales= total_sales + 1
WHERE genre= NEW.category_name ;
RETURN NEW;
END;
$$ ;
CREATE TRIGGER increment_summary
AFTER INSERT
ON category_performance_summary
FOR EACH STATEMENT
EXECUTE PROCEDURE increment_summary_table();
CREATE OR REPLACE FUNCTION decrement_summary_table()
RETURNS TRIGGER
LANGUAGE PLPGSQL
AS
$$
BEGIN
UPDATE category_performance_summary
SET total_sales= total_sales - 1
WHERE genre= OLD.category_name ;
RETURN OLD;
END;
$$ ;
CREATE TRIGGER decrement_summary
AFTER DELETE
ON category_performance_summary
FOR EACH STATEMENT
EXECUTE PROCEDURE decrement_summary_table();
I want to create a trigger function, which copies certain columns of an recent updated row and deletes the old data. After that I want to insert the copied columns in exact the same table in the same row (overwrite). I need the data to be INSERTED because this function will be embedded in an existing program, with predefined Triggers.
That's what I have so far:
CREATE OR REPLACE FUNCTION update_table()
RETURNS TRIGGER AS
$func$
BEGIN
WITH tmp AS (DELETE FROM table
WHERE table.id = NEW.id
RETURNING id, geom )
INSERT INTO table (id, geom) SELECT * FROM tmp;
END;
$func$ language plpgsql;
CREATE TRIGGER T_update
AFTER UPDATE OF geom ON table
EXECUTE PROCEDURE update_table();
But I get the Error message:
ERROR: cannot perform DELETE RETURNING on relation "table"
HINT: You need an unconditional ON DELETE DO INSTEAD rule with a RETURNING clause.
Why I should use a rule here?
I'm using PostgreSQL 9.6
UPDATE:
A little bit of clarification. When I have two columns in my table (id, geom), after I updated geom I want to make a copy of this (new)row and insert it into the same table, while overwriting the updated row. (I'm not interested in any value before the update) I know that this is odd but I need this row to be inserted again because the program i embed this function in, listens to a INSERT statement and cannot be changed by me.
Right after you update a row, its old values will no longer be available. So, if you simply want to preserve the old row in case of an update you need to create a BEFORE UPDATE trigger, so that you can still access the OLD values and create a new row, e.g.
CREATE TABLE t (id int, geom geometry(point,4326));
CREATE OR REPLACE FUNCTION update_table() RETURNS TRIGGER AS $$
BEGIN
INSERT INTO t (id, geom) VALUES (OLD.id,OLD.geom);
RETURN NEW;
END; $$ LANGUAGE plpgsql;
CREATE TRIGGER t_update
BEFORE UPDATE OF geom ON t FOR EACH ROW EXECUTE PROCEDURE update_table();
INSERT INTO t VALUES (1,'SRID=4326;POINT(1 1)');
If you update the record 1 ..
UPDATE t SET geom = 'SRID=4326;POINT(2 2)', id = 2 WHERE id = 1;
UPDATE t SET geom = 'SRID=4326;POINT(3 3)', id = 3 WHERE id = 2;
.. you get a new record in the same table as you wished
SELECT id, ST_AsText(geom) FROM t;
id | st_astext
----+------------
1 | POINT(1 1)
2 | POINT(2 2)
3 | POINT(3 3)
Demo: db<>fiddle
Unrelated note: consider upgrading your PostgreSQL version! 9.6 will reach EOL in November, 2021.
First thanks to #JimJones for the answer. I´d like to post his answer modified for this purpose. This code "overwrites" the updated row by inserting a copy of itself and then deleting the old duplicate. That way I can Trigger on INSERT.
CREATE TABLE t (Unique_id SERIAL,id int, geom geometry(point,4326));
CREATE OR REPLACE FUNCTION update_table() RETURNS TRIGGER AS $$
BEGIN
INSERT INTO t (id, geom) VALUES (NEW.id,NEW.geom);
RETURN NEW;
END;
$$ LANGUAGE plpgsql;
CREATE TRIGGER t_update
BEFORE UPDATE OF geom ON t FOR EACH ROW EXECUTE PROCEDURE update_table();
CREATE OR REPLACE FUNCTION delete_table() RETURNS TRIGGER AS $$
BEGIN
DELETE FROM t a
USING t b
WHERE a.Unique_id < b.Unique_id
AND a.geom = b.geom;
RETURN NEW;
END;
$$ LANGUAGE plpgsql;
CREATE TRIGGER t_delete
AFTER UPDATE OF geom ON t FOR EACH ROW EXECUTE PROCEDURE delete_table();
INSERT INTO t VALUES (1,1,'SRID=4326;POINT(1 1)');
UPDATE t SET geom = 'SRID=4326;POINT(2 2)' WHERE id = 1;
I have a really simple problem and I am probably overthinking this way too much. But here it goes:
I want the fields of a column in one of my tables to be filled automatically whenever I make a new record. The value should be the same (UUID) as the specified (UUID) value from a column in another table. These two columns are joined via a foreign key. So far I have tried making a trigger function but with no results so far:
Create or replace function project_id()
returns trigger
as $$ begin
if new.project_id is null then
insert into sporen (project_id)
select project_id
from project_info
where project_code = 'ant0001';
end if;
return new;
end;
$$ language plpgsql;
CREATE TRIGGER
project_id_default
BEFORE update ON
sporen
FOR EACH ROW EXECUTE PROCEDURE project_id();
Do I need to specify something as a default in my table? Or am I going about it completely wrong?
You only need to assign project_info.project_id to NEW.project_id in your trigger function. No INSERT is needed. Here is an illustration.
Create or replace function project_id() returns trigger as
$$
begin
if new.project_id is null then
new.project_id :=
(
select pi.project_id
from project_info pi
where pi.project_code = NEW.project_code
);
end if;
return new;
end;
$$ language plpgsql;
You do not need to specify a default value for project_id in your table.
I have a stored procedure to perform an upsert. However the conflict condition never runs, passing an existing ID always causes it to create a new record.
create or replace function upsert_email(v_id bigint, v_subject character varying)
returns bigint
language plpgsql
as $$
declare
v_id bigint;
begin
insert into emails
(id, subject)
values (coalesce(v_id, (select nextval('serial'))), v_subject)
on conflict(id)
do update set (subject) = (v_subject) where emails.id = v_id
returning id into v_id;
return v_id;
end;
$$;
When running select upsert_email(6958500, 'subject'); which is a record that exists, it always creates a new record instead.
I have already looked at: Upsert/on conflict with serial primary key which is the most similar question and is what my SQL is modeled on, however I haven't been able to get it to work.
Wow, idiot of the year award goes to me.
I'm taking a parameter called v_id, then immediately overwrite it in the declare with a v_id; They should be named 2 different things:
create or replace function upsert_email(v_id bigint, v_subject character varying)
returns bigint
language plpgsql
as $$
declare
v_return_id bigint;
begin
insert into emails
(id, subject)
values (coalesce(v_id, (select nextval('serial'))), v_subject)
on conflict(id)
do update set (subject) = (v_subject) where emails.id = v_id
returning id into v_return_id;
return v_return_id;
end;
$$;
I´ve got this sample from another thread and it fits perfectly on what I need to know.
CREATE SEQUENCE AlimentosSequencia;
CREATE TABLE alimento (
id integer NOT NULL PRIMARY KEY
,name VARCHAR(255));
CREATE OR REPLACE FUNCTION AlimentoFuncion()
RETURNS "trigger" AS
$BODY$
BEGIN
New.id:=nextval('AlimentosSequencia');
Return NEW;
END;
$BODY$
LANGUAGE 'plpgsql' VOLATILE;
CREATE TRIGGER AlimentosTrigger
BEFORE INSERT
ON alimento
FOR EACH ROW
EXECUTE PROCEDURE AlimentoFuncion();
INSERT INTO alimento (name) VALUES ('lemon');
This is working fine! But I have to complement the function AlimentoFunction.
Is there any way to check IN THE FUNCTION if my insert statement is placing an ID?
Example:
INSERT INTO alimento (name) VALUES ('lemon');
Ok this, works... and If I do that:
INSERT INTO alimento (id, name) VALUES (299, 'lemon');
My function must check if the sequence has to be used.
I know I can set the default value of ID to be the sequence on the table creation, but I can't modify that.. I just can change the trigger function.
Something like:
if new.id is NULL then
New.id:=nextval('AlimentosSequencia');
end if;