I have subscription data that is being appended to a table in real-time (via kafka). i have set up a trigger such that once the data is added it is checked for consistency. If checks pass some of the data should be added to other tables (that have master information on the customer profile etc.). The checks function i wrote works fine but i keep getting errors on the function used in the trigger. The function for the trigger is:
CREATE OR REPLACE FUNCTION update_tables()
RETURNS TRIGGER
LANGUAGE plpgsql
AS
$$
BEGIN
CASE (SELECT check_incoming_data()) WHEN 0
THEN INSERT INTO
sub_master(sub_id, sub_date, customer_id, product_id)
VALUES(
(SELECT sub_id::int FROM sub_realtime WHERE CTID = (SELECT MAX(CTID) FROM sub_realtime)),
(SELECT sub_date::date FROM sub_realtime WHERE CTID = (SELECT MAX(CTID) FROM sub_realtime)),
(SELECT customer_id::int FROM sub_realtime WHERE CTID = (SELECT MAX(CTID) FROM sub_realtime)),
(SELECT product_id::int FROM sub_realtime WHERE CTID = (SELECT MAX(CTID) FROM sub_realtime))
);
RETURN sub_master;
END CASE;
RETURN sub_master;
END;
$$
The trigger is then:
CREATE TRIGGER incoming_data
AFTER INSERT
ON claims_realtime_3
FOR EACH ROW
EXECUTE PROCEDURE update_tables();
What I am saying is 'if checks pass then select data from the last added row and add them to the master table'. What is the best way to structure this query?
Thanks a lot!
The trigger functions are executed for each row and you must use a record type variable called "NEW" which is automatically created by the database in the trigger functions. "NEW" gets only inserted records. For example, I want to insert data to users_log table when inserting records to users table.
CREATE OR REPLACE FUNCTION users_insert()
RETURNS trigger
LANGUAGE plpgsql
AS $function$
begin
insert into users_log
(
username,
first_name,
last_name
)
select
new.username,
new.first_name,
new.last_name;
return new;
END;
$function$;
create trigger store_data_to_history_insert
before insert
on users for each row execute function users_insert();
Related
I'm trying to set an "after insert" trigger that executes a procedure. The procedure would take all inserted rows in table A, group them by a column and insert the result in a table B. I know about "new" variable but it gets inserted rows one by one. Is it possible to get all of them?
I think I can't use a for each row statement as I need to group rows depending on the "trackCode" variable, shared by different rows in tableA.
CREATE OR REPLACE PROCEDURE Public.my_procedure(**inserted rows in tableA?**)
LANGUAGE 'plpgsql'
AS $$
BEGIN
INSERT INTO Public."tableB" ("TrackCode", "count")
SELECT "TrackCode", count(*) as "count" FROM Public."tableA" --new inserted rows in this table
GROUP BY "vmsint"."TrackCode" ;
COMMIT;
END;
$$;
create trigger Public.my_trigger
after insert ON Public.tableA
execute procedure Public.my_procedure(**inserted rows in tableA?**)
Thank you!
You create a statement lever trigger, but do not attempt to pass parameters. Instead use the clause referencing new table as reference_table_name. In the trigger function you use the reference_table_name in place of the actual table name. Something like: (see demo)
create or replace function group_a_ais()
returns trigger
language 'plpgsql'
as $$
begin
insert into table_b(track_code, items)
select track_code, count(*)
from rows_inserted_to_a
group by track_code ;
return null;
end;
$$;
create trigger table_a_ais
after insert on table_a
referencing new table as rows_inserted_to_a
for each statement
execute function group_a_ais();
Do not attempt to commit in a trigger, it is a very bad id even if allowed. Suppose the insert to the main table is part of a larger transaction, which fails later in its process.
Be sure to refer to links provided by Adrian.
I have these tables:
Users
Skills (name - string, count - integer)
Has_skills (skill_id - skills.id, user_id users.id)
Has_skills is a many to many table between the first two through these FK:
user_id (users.id) and skill_id (skills.id).
What I want to do is update the count column inside skills when a new row is inserted into has_skills. I want to do this through an update trigger on table has_skills. The new value for count I will get through a select query:
SELECT COUNT(*) AS cnt FROM skills
JOIN has_skills hs ON skills.id = hs.skill_id
WHERE hs.skill_id = 1;
The ID above is hardcoded (1), but it works.
I also tested this code in isolation, and it works (although hardcoded, as well):
UPDATE skills
SET count = subquery.cnt
FROM (
SELECT COUNT(*) AS cnt FROM skills
JOIN has_skills hs ON skills.id = hs.skill_id
WHERE hs.skill_id = 1
) AS subquery
WHERE skills.id = 1;
RETURN NEW;
Alright, so here's probably where the problem is. Below is the trigger function and also the trigger itself.
Function:
CREATE OR REPLACE FUNCTION update_skill_count() RETURNS trigger AS
$func$
BEGIN
UPDATE skills
SET count = subquery.cnt
FROM (
SELECT COUNT(*) AS cnt FROM skills
JOIN has_skills hs ON skills.id = hs.skill_id
WHERE hs.skill_id = NEW.skill_id
) AS subquery
WHERE skills.id = NEW.skill_id;
RETURN NEW;
END;
$func$ LANGUAGE plpgsql;
Trigger:
CREATE TRIGGER on_has_skills_insert
AFTER INSERT ON has_skills
FOR EACH ROW
EXECUTE PROCEDURE update_skill_count();
I successfully create the function and trigger, but when I insert new data into has_skills, it doesn't change the count column inside skills. What could be the problem?
There's no need for a select in the trigger function at all. The key for the skill table is directly available in new.skill_id so just use it directly:
-- trigger function and trigger
create or replace function update_skill_count()
returns trigger
as $func$
begin
update skills sk
set count = count+1
where sk.skill_id = new.skill_id;
return new;
end;
$func$ language plpgsql;
create trigger on_has_skills_insert
after insert on has_skills
for each row
execute procedure update_skill_count();
I'm not much familiar with postgresql, but having understanding of Oracle and SQL Server, this looks to be a mutating trigger problem, which is: Trying to read from or write into the same table within a row level trigger on which the trigger is placed.
One of the ways to get rid of mutating trigger/table problem can be changing the row level trigger to a statement level trigger and changing the function accordingly. Here is a psudo code you can try out (not providing the exact tested code as I do not have Postgresql installed):
Function:
CREATE OR REPLACE FUNCTION update_skill_count() RETURNS trigger AS
$func$
BEGIN
UPDATE skills
SET count = subquery.cnt
FROM (
SELECT hs.skill_id, COUNT(*) AS cnt
FROM new_table hs
GROUP BY hs.skill_id
) AS subquery
WHERE skills.id = subquery.skill_id;
RETURN NULL;
END;
$func$ LANGUAGE plpgsql;
Trigger:
CREATE TRIGGER on_has_skills_insert
AFTER INSERT ON has_skills
REFERENCING NEW TABLE AS new_table
FOR EACH STATEMENT EXECUTE PROCEDURE update_skill_count();
I came from Microsoft SQL environment.I have two tables tak_ne and tak_beb and my requirement was to insert values from tak_beb to tak_ne if value is not present,if it is present just update.So i made a merge statement as shown below.But the problem now i am facing is veryday 50000 count is getting increment for sequence number.Oracle is stable database, and i don't know why they made it like that.So i create a Function and prevented incrementing sequence number.My question is ,is it a right approach by creating function.Following is what i did
merge into tak_ne a using tak_beb b ON (a.NAME=b.NAME)
When matched then
Update
Set a.AC_NO = b.AC_NO
a.LOCATION = b.LOCATION
a.MODEL = b.MODEL
When not matched then
insert
(
sl_no,
AC_NO,
LOCATION
MODEL
)
Values
(
s_slno_nextval
b.AC_NO
b.LOCATION
b.MODEL
)
and then i created a function
CREATE OR REPLACE FUNCTION s_slno_nextval
RETURN NUMBER
AS
v_nextval NUMBER;
BEGIN
SELECT s_emp.nextval
INTO v_nextval
FROM dual;
RETURN v_nextval;
END;
Oracle uses this approach to generate unique id for each row inserted by a statement. Your TAK_BEB table has probably 50000 rows, so the sequence is incremented 50000 times.
To hide increment into a function does not help. Function is called AND EXECUTED for every row, it increments sequence for 50000 times again. And it adds overhead with 50000 selects from dual table.
If you really need to use ONE value from sequence for ALL rows inserted by statement, use package variable:
create package single_id_pkg is
id Number;
function get_id return number;
end;
/
create or replace package body single_id_pkg is
function get_id return number is
begin
return id;
end;
end;
/
Now use for example before statement trigger on table to set the variable:
create trigger tak_ne_BSI_trg
before insert
on tak_ne
begin
select s_emp.nextval
into single_id_pkg.id
from dual;
end;
Insert trigger has one disadvantage - with MERGE clause it fires even if the statement does only updates rows (see https://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:25733900083512). If it is a problem, you have to initialize the variable in other way.
Next modify your statement to use a package variable:
merge into tak_ne a
using tak_beb b
on (a.NAME=b.NAME)
when matched then
update
set a.AC_NO = b.AC_NO
a.LOCATION = b.LOCATION
a.MODEL = b.MODEL
when not matched then
insert (sl_no,
AC_NO,
LOCATION,
MODEL)
values (single_id_pkg.get_id
b.AC_NO,
b.LOCATION,
b.MODEL)
In Oracle standard way to use autoincrement field is by using sequences. And of course it will increment sequence number each time you want to use it.
But you can omit calling sequence_name.nextval, hiding it in trigger it is considered the standard approach also.
CREATE OR REPLACE EDITIONABLE TRIGGER TAK_NE_ID_TR"
BEFORE INSERT ON tak_ne
FOR EACH ROW
BEGIN
IF :old.sl_no IS NULL THEN
:new.sl_no := s_emp.nextval;
END IF;
END;
If you want to add same id for a batch of your inserts you can use global temporary table for saving it. For example, like this:
create global temporary table tak_ne_id ("id" number) on commit delete rows
create or replace trigger tak_ne_BSI_trg
before insert
on tak_ne
begin
insert into tak_ne_id("id")
values(s_emp.nextval);
end
create or replace TRIGGER TAK_NE_ID_TR
BEFORE INSERT ON tak_ne
FOR EACH ROW
BEGIN
if :old.sl_no is null then
SELECT "id"
INTO :new.sl_no
FROM tak_ne_id;
end if;
END;
Then you can use you merge as before, and without calling nextval:
merge into tak_ne a using tak_beb b ON (a.NAME=b.NAME)
When matched then
update
set a.AC_NO = b.AC_NO,
a.LOCATION = b.LOCATION,
a.MODEL = b.MODEL
When not matched then
insert
(
AC_NO,
LOCATION,
MODEL
)
Values
(
b.AC_NO,
b.LOCATION,
b.MODEL
);
I want only to maintain present 1 month records log details. need to delete past record log details.I tried this code however could not work this,
create sequence userseq1;
CREATE TABLE users
( id integer NOT NULL DEFAULT nextval('userseq1'::regclass)
);
INSERT INTO users VALUES(126);
CREATE TABLE History
( userid integer
, createdate timestamp
);
CREATE OR REPLACE FUNCTION recordcreatetime() RETURNS trigger language plpgsql
AS $$
DECLARE
BEGIN
INSERT INTO History values(new.id,NOW() );
RETURN NEW;
END;
$$;
CREATE TRIGGER user_hist
BEFORE INSERT ON users
FOR EACH ROW
EXECUTE procedure recordcreatetime();
However it is working to insert values sequencing one by one adding.I want to delete the previous 1 month record Log details.I tried this below code and it is not working
CREATE OR REPLACE FUNCTION trf_keep_row_number_steady()
RETURNS TRIGGER AS
$body$
DECLARE
BEGIN
IF (SELECT count(createdate) FROM history) > rownum_limit
THEN
DELETE FROM history
WHERE createdate = (SELECT min(createdate) FROM history);
END IF;
END;
$body$
LANGUAGE plpgsql;
CREATE TRIGGER tr_keep_row_number_steady
AFTER INSERT ON history
FOR EACH ROW EXECUTE PROCEDURE trf_keep_row_number_steady();
I can see in your second code block, you have a trigger on history table and you are trying to DELETE FROM history in that same trigger.
Insert / Update / Delete on a table through a trigger on the same table is not allowed. Please think of some other alternative, e.g., running a separate DELETE statement for the required cleanup of rows before or after your main INSERT statement.
I want to create a trigger for my view in PostgreSQL. The idea is that all new data must fulfill a condition to be inserted. But something is wrong here and I can't find the answer in manuals.
CREATE OR REPLACE VIEW My_View AS
SELECT name, adress, count FROM club, band, country;
CREATE OR REPLACE FUNCTION insert() RETURNS TRIGGER AS $$
BEGIN
IF(NEW.count > 10) THEN
INSERT INTO My_View VALUES (NEW.name, NEW.adress, NEW.count);
END IF;
END;
$$ LANGUAGE plpgsql;
CREATE TRIGGER insert INSTEAD OF INSERT ON My_View
FOR EACH ROW EXECUTE PROCEDURE insert();
There is a semicolon ( ; ) missing at the end of the INSERT statement in the function.
insert is a reserved word in the SQL standard and should not be used as trigger or function name. Even if it's allowed in PostgreSQL, it's a very bad idea.
There are no join conditions for the three tables club, band, country in your view definition. This leads to a CROSS JOIN, which can be extremely expensive. If there are 1000 rows in each table, you get 1,000,000,000 combinations. You most definitely do not want that.
Also, you should table-qualify the columns in your view definition to avoid ambiguities.
CREATE OR REPLACE VIEW my_view AS
SELECT ??.name, ??.address, ??.mycount
FROM club cl
JOIN band ba ON ?? = ??
JOIN country co ON ?? = ??;
You need to fill in where I left question marks.
And always add a column definition list to your INSERT statements.
And finally, you do not want to INSERT into the same view again, which would create an endless loop and may be the primary cause of your error.
CREATE OR REPLACE FUNCTION f_insert()
RETURNS TRIGGER AS
$func$
BEGIN
IF NEW.mycount > 10 THEN
INSERT INTO my_view ???? (col1?, col2?, col3?)
VALUES (NEW.name, NEW.address, NEW.mycount);
END IF;
END
$func$ LANGUAGE plpgsql;
BTW, you shouldn't use count as identifier either. I use mycountinstead.