TRIGEER-->To get a column value from one table to other table when i insert values?
I am having two tables(customer_details and loan_balance).
What i need is, I must get the column (custid)of customer_details table to the loan_balance table when i insert the data into the loan_balance table.
This is the full set up of my query : SQL FIDDLE
So i need a trigger to be raised and the data should be updated automatically without dynamic insertion of custid.
Postgres has an unconventional way of creating triggers:
create a function that returns type trigger and return the NEW row record
create a trigger that executes the function
Here's the code you need:
CREATE FUNCTION synch_custid_proc()
RETURNS trigger AS $$
BEGIN
NEW.custid = (
select max(custid)
from customer_details
where creditid = NEW.creditid
);
RETURN NEW;
END;
$$ LANGUAGE plpgsql
CREATE TRIGGER synch_custid_trig
BEFORE INSERT ON loan_amount
FOR EACH ROW
EXECUTE PROCEDURE synch_custid_proc();
I chosen to select max(custid) rather than simply custid when finding the value in case there are multiple rows that match. You might have to adjust this logic to suit your data.
See a live demo on SQLFiddle
Related
I have an already made table:
cotizacion(idCot(PK), unit_price,unit_price_taxes)
I need to convert unit_price_taxes into a generated column that is equal to unit_price*1.16. The issue is I can't find the alter table statement which will give me this. Dropping table and creating it again is not an option as this table is already deeply linked with the rest of the database and reinserting all records is not an option at this point.
I tried the following:
ALTER TABLE cotizacion
alter column unit_price_taxes set
GENERATED ALWAYS AS (unit_price*1.16) STORED;
But it's not working. Does anybody know how to get this done or if it's even possible? I would like to avoid creating a new column.
Thanks!
**EDIT:
I also tried the following trigger implementation:
CREATE OR REPLACE FUNCTION calculate_price_taxes()
RETURNS trigger
LANGUAGE plpgsql
AS $function$
declare pu money;
begin
select unit_price from cotizacion into pu
where idCot = new."idCot";
update cotizacion
set unit_price_taxes = pu * (1.16)
where idCot = new."idCot";
return new;
end;
$function$
;
And the trigger delcaration:
Create or replace trigger price_taxes
after update on cotizacion
for each row
execute procedure
calculate_price_taxes()
The most probable reason for your trigger to go into an infinite recursion is that you are running an UPDATE statement inside the trigger - which is the wrong thing to do. Create a before trigger and assign the calculated value to the new record:
create trigger update_tax()
returns trigger
as
$$
begin
new.unit_price_taxes := unit_price * 1.16;
return new;
end;
$$
language plpgsql;
create trigger update_tax_trigger()
before update or insert on cotizacion
for each row execute procedure update_tax();
The only way to "convert" that column to a generated one, is to drop it and add it again:
alter table cotizacion
drop unit_price_taxes;
alter table cotizacion
add unit_price_taxes numeric generated always as (unit_price*1.16) stored;
Note that this will rewrite the entire table which will block access to it. Adding the trigger will be less invasive.
I am trying to write a trigger which gets data from the table attribute in which multiple rows are inserted corresponding to one actionId at one time and group all that data into the one object:
Table Schema
actionId
key
value
I am firing trigger on rows insertion,SO how can I handle this multiple row insertion and how can I collect all the data.
CREATE TRIGGER attribute_changes
AFTER INSERT
ON attributes
FOR EACH ROW
EXECUTE PROCEDURE log_attribute_changes();
and the function,
CREATE OR REPLACE FUNCTION wflowr222.log_task_extendedattribute_changes()
RETURNS trigger AS
$BODY$
DECLARE
_message json;
_extendedAttributes jsonb;
BEGIN
SELECT json_agg(tmp)
INTO _extendedAttributes
FROM (
-- your subquery goes here, for example:
SELECT attributes.key, attributes.value
FROM attributes
WHERE attributes.actionId=NEW.actionId
) tmp;
_message :=json_build_object('actionId',NEW.actionId,'extendedAttributes',_extendedAttributes);
INSERT INTO wflowr222.irisevents(message)
VALUES(_message );
RETURN NULL;
END;
$BODY$
LANGUAGE plpgsql VOLATILE
COST 100;
and data format is,
actionId key value
2 flag true
2 image http:test.com/image
2 status New
I tried to do it via Insert trigger, but it is firing on each row inserted.
If anyone has any idea about this?
I expect that the problem is that you're using a FOR EACH ROW trigger; what you likely want is a FOR EACH STATEMENT trigger - ie. which only fires once for your multi-line INSERT statement. See the description at https://www.postgresql.org/docs/current/sql-createtrigger.html for a more through explanation.
AFAICT, you will also need to add REFERENCING NEW TABLE AS NEW in this mode to make the NEW reference available to the trigger function. So your CREATE TRIGGER syntax would need to be:
CREATE TRIGGER attribute_changes
AFTER INSERT
ON attributes
REFERENCING NEW TABLE AS NEW
FOR EACH STATEMENT
EXECUTE PROCEDURE log_attribute_changes();
I've read elsewhere that the required REFERENCING NEW TABLE ... syntax is only supported in PostgreSQL 10 and later.
Considering the version of postgres you have, and therefore keeping in mind that you can't use a trigger defined FOR EACH STATEMENT for your purpose, the only alternative I see is
using a trigger after insert in order to collect some information about changes in a utility table
using a unix cron that execute a pl/sql that do the job on data set
For example:
Your utility table
CREATE TABLE utility (
actionid integer,
createtime timestamp
);
You can define a trigger FOR EACH ROW with a body that do something like this
INSERT INTO utilty values(NEW.actionid, curent_timestamp);
And, finally, have a crontab UNIX that execute a file or a procedure that to something like this:
SELECT a.* FROM utility u JOIN yourtable a ON a.actionid = u.actionid WHERE u.createtime < current_timestamp;
// do something here with records selected above
TRUNCATE table utility;
If you had postgres 9.5 you could have used pg_cron instead of unix cron...
I'm trying to, somehow, trigger a automatic function drop when a table is dropped and I can't figure out how to do it.
TL;DR: Is there a way to trigger a function drop when a specific table is dropped? (POSTGRESQL 11.7)
Detailed explanation
I'll try to explain my problem using a simplified use case with dummy names.
I have three tables: sensor1, sensor2 and sumSensors;
A FUNCTION (sumdata) was created to INSERT data on sumSensors table. Inside this function I'll fetch data from sensor1 and sensor2 tables and insert its sum on table sumSensors;
A trigger was created for each sensor table which like this:
CREATE TRIGGER trig1
AFTER INSERT ON sensor1
FOR EACH ROW EXECUTE
FUNCTION sumdata();
Now, when a new row is inserted on tables sensor1 OR sensor2, the function sumdata will be executed and insert the sum of last values from both on table sumSensors
If I wanted to DROP FUNTION sumdata CASCADE;, the triggers would be automatically removed from tables sensor1 and sensor2. Until now that's everything fine! But that's not what I want.
My problem is:
Q: And if I just DROP TABLE sumSensors CASCADE;? What would happen to the function which was meant to insert on this table?
A: As expected, since there's no association between sumSensors table and sumdata function, the function won't be dropped (still exist)! The same happens to the triggers which use it (still exist). This means that when a new row is inserted on sensor tables, the function sumdata will be executed and corrupted, leading to a failure (even the INSERT which triggered the function execution won't be actually inserted).
Is there a way to trigger a function drop when a specific table is dropped?
Thank you in advance
There is no dependency tracking for functions in PostgreSQL (as of version 12).
You can use event triggers to maintain the dependencies yourself.
Full example follows.
More information: documentation of event triggers feature, support functions.
BEGIN;
CREATE TABLE _testtable ( id serial primary key, payload text );
INSERT INTO _testtable (payload) VALUES ('Test data');
CREATE FUNCTION _testfunc(integer) RETURNS integer
LANGUAGE SQL AS $$ SELECT $1 + count(*)::integer FROM _testtable; $$;
SELECT _testfunc(100);
CREATE FUNCTION trg_drop_dependent_functions()
RETURNS event_trigger
LANGUAGE plpgsql AS $$
DECLARE
_dropped record;
BEGIN
FOR _dropped IN
SELECT schema_name, object_name
FROM pg_catalog.pg_event_trigger_dropped_objects()
WHERE object_type = 'table'
LOOP
IF _dropped.schema_name = 'public' AND _dropped.object_name = '_testtable' THEN
EXECUTE 'DROP FUNCTION IF EXISTS _testfunc(integer)';
END IF;
END LOOP;
END;
$$;
CREATE EVENT TRIGGER trg_drop_dependent_functions ON sql_drop
EXECUTE FUNCTION trg_drop_dependent_functions();
DROP TABLE _testtable;
ROLLBACK;
I have a table, on which I want to update multiple columns when a new row is inserted. My current trigger, which only updates a single column, looks like the below (simplified):
CREATE OR REPLACE FUNCTION func_only_updates_one_column()
RETURNS trigger AS
$BODY$
BEGIN
NEW.one_column := (SELECT rslt.one_column FROM
(SELECT one_column, two_column, three_column, more_column
FROM NEW
JOIN a_very_complicated_query avcq
ON avcq.one_column = NEW.one_column
AND avcq.two_column = NEW.two_column) rslt;
RETURN NEW;
END
$BODY$
LANGUAGE 'plpgsql';
CREATE TRIGGER trig_update_table BEFORE INSERT on target_table
FOR EACH ROW EXECUTE PROCEDURE func_only_updates_one_column();
I could create another trigger for my other column with the same logic, or run the query multiple times, but I don't want to run a SELECT from a_very_complicated_query multiple times - it's quite expensive as-is, and my application depends on this query being fast.
How can I update multiple columns in a BEFORE INSERT trigger with a single subquery referring to the NEW row? I only want to run the SQL once. I am using Postgresql 11.
That would simply work like this:
SELECT rslt.one_column,
rslt.two_column,
...
INTO NEW.one_column,
NEW.two_column,
...
FROM /* your complicated query */
I have a problem I am stuck on for some time now. So I wanted to reach out for a little help.
I have 2 tables which are holding the same data: transactions and transactions2.
I want to write a Trigger that is triggering every time a new row is added to transactions and insert it into transaction2 in PLSQL.
First I simply duplicated the table with
CREATE TABLE transactions2 (SELECT * FROM transactions WHERE 1=1);
I think I found out how to insert
CREATE OR REPLACE FUNCTION copyRow RETURNS TRIGGER AS $$
DECLARE
BEGIN
INSERT INTO transaction2
VALUES transaction;
END;
I think the syntax with this is also wrong, but how do I say, that the Trigger should start as soon as a new Insert into the first table is made?
Can anyone help me with this?
Thanks
Bobby
The correct syntax for an INSERT is INSERT (<column list>) VALUES (<values list>). The INSERT syntax isn't different in a function compared to "outside". So your trigger function should look something like:
CREATE OR REPLACE FUNCTION t2t2_f ()
RETURNS TRIGGER
AS
$$
BEGIN
INSERT INTO transactions2
(column_1,
...,
column_n)
VALUES (NEW.column_1,
...,
NEW.column_n);
RETURN NEW;
END;
$$
LANGUAGE plpgsql;
Replace the column_is with the actual column names of your table. NEW is a pseudo record with which you can access the values of the new row.
To create the trigger itself use something like:
CREATE TRIGGER t2t2_t
AFTER INSERT
ON transactions
FOR EACH ROW
EXECUTE PROCEDURE t2t2_f();
You may want to use another timing, e.g. BEFORE instead of AFTER.
That should give you something to start with. Please consider studying the comprehensive PostgreSQL Manual for further and more detailed information.