So, I understand how to create a trigger in HANA, but the examples in the HANA reference material do not mention how a trigger on Table A can update Table A; instead the material is always trigger on A updates B like the following example from the SAP docs:
CREATE TRIGGER TEST_TRIGGER_VAR_UPDATE
AFTER UPDATE ON TARGET
REFERENCING NEW ROW mynewrow, OLD ROW myoldrow
FOR EACH ROW
BEGIN
INSERT INTO SAMPLE_new VALUES(:mynewrow.a, :mynewrow.b);
INSERT INTO SAMPLE_old VALUES(:myoldrow.a, :myoldrow.b);
INSERT INTO SAMPLE VALUES(0, 'trigger');
END;
What's the preferred way of updating a column such as a LastModifiedDate? Would I set :mynewrow.LastModifiedDate = NOW(), or should I perform an UPDATE where the ID matches the ID of mynewrow?
As of SPS8, a HANA SQL Trigger can only perform INSERT, UPDATE, and DELETE statements against other tables. If you try to create a self-referencing Trigger, you'll find the following error message:
Modification of subject table in trigger not allowed
Related
I am trying to make an upsert trigger on ORACLE via PL/SQL by checking some examples, i am doing fine, i think it is the last step i should only configure. My requirement is that :
A system that will insert to that field will remain one column always null, so i will read column value from another table, then upsert it with inclusion of that value.
d2c_region_locale_config holds d2c_is_active value, so i firstly read that value regarding to locale condition then trigger inserts or updates to table with addition of this value on active_for_d2c column.(for update i am using locale and country columns as it is shown on where clause, they are not PK but has not null condition)
So i've created this trigger:
CREATE OR REPLACE TRIGGER BL_PIM_LOCALE_COUNTRY
BEFORE INSERT OR UPDATE ON PIM_LOCALE_COUNTRY REFERENCING NEW AS NEW OLD AS OLD
FOR EACH ROW
DECLARE
l_active_for_d2c INTEGER;
BEGIN
if :NEW.active_for_d2c is null then
DELETE from pim_locale_country where active_for_d2c is null;
select distinct(d2c_isactive) into l_active_for_d2c from d2c_region_locale_config where d2c_locale= :NEW.locale;
UPDATE pim_locale_country
SET locale = :NEW.locale, locale_name = :NEW.locale_name,
country = :NEW.country, country_name = :NEW.country_name, isdummy = :NEW.isdummy,
active_for_d2c = l_active_for_d2c, itextpos = :NEW.itextpos, locale_charset = :NEW.locale_charset,
fallback_locale = :NEW.fallback_locale, default_for_lang = :NEW.default_for_lang, opeclang = :NEW.opeclang
where locale = :NEW.locale and country = :NEW.country;
IF ( sql%notfound ) THEN
INSERT INTO PIM_LOCALE_COUNTRY (locale,locale_name,country,country_name,isdummy,active_for_d2c,itextpos,locale_charset,fallback_locale,default_for_lang,opeclang)
VALUES (:NEW.locale, :NEW.locale_name,:NEW.country,:NEW.country_name,:NEW.isdummy,l_active_for_d2c,:NEW.itextpos,:NEW.locale_charset,:NEW.fallback_locale,:NEW.default_for_lang,:NEW.opeclang);
END IF;
end if;
END;
It currently does the job, reads value and inserts or updates the existing locale-country couple for other values. But critical thing is that, table always has one "null" value(Please check screenshot), even that i run delete statement at the beginning on my trigger. So my question would be how to delete, or how to make this approach on trigger side ?
Many thanks for answers!
Trigger before insert doesn't block insert itself, so you insert that record twice. That is, once your trigger done its work (inserted or updated record), oracle will proceed with insert (or update) using values that stand in NEW record of your trigger. If trigger modifies NEW., it will be stored as you changed it, but if trigger inserts something itself, you can get more records.
You can use instead of insert or update triggers, and then oracle will not run its own inserts/updates after trigger finishes.
But more common way for 1-record triggers is to modify fields in NEW, for this case field NEW.d2c_is_active.
It looks like this (possible typos, please check)
CREATE OR REPLACE TRIGGER BL_PIM_LOCALE_COUNTRY
BEFORE INSERT OR UPDATE ON PIM_LOCALE_COUNTRY REFERENCING NEW AS NEW OLD AS OLD
FOR EACH ROW
BEGIN
if :NEW.active_for_d2c is null then
select d2c_isactive
into :NEW.active_for_d2c
from d2c_region_locale_config
where d2c_locale= :NEW.locale and rownum<=1;
end if;
END;
I am trying to write a trigger in SAP HANA to update a field of a table when new records are being inserted to that table. Following is a sample trigger that I have written.
CREATE TRIGGER SAMPLE
AFTER INSERT ON TARGET_TABLE
REFERENCING NEW ROW NEW_ROW
FOR EACH ROW
BEGIN
UPDATE TARGET_TABLE SET VALID_FROM='2018-02-01' WHERE ITEM=:NEW_ROW.ITEM
END
When I try this, I get the error:
Modification of subject table in trigger not allowed
Is there a way by which I can achieve this?
This suggests to use the transition variable NEW_ROW, appreciate if a code sample can be provided.
You don't actually need to create trigger for your requirement as I can see from your post (of course if it is only updating a date field)
You can define the VALID_FROM column with a DEFAULT value
For example,
Create Column Table DefaultColumnTable (
Id int,
Code varchar(5),
VALID_FROM date default '2018-02-01'
)
So whenever a new row is inserted, unless an alternative value is stated the valid_from column will be populated with default date specified in the DDL command above.
The users can change the valid_from field value without any problem
#Kalpa, maybe you can use BEFORE INSERT Trigger
Please check following sample
create trigger TriggerTable_B_INS BEFORE INSERT on TriggerTable
REFERENCING NEW ROW mynewrow
FOR EACH ROW
begin
declare lv_d date;
lv_d := '20180201';
mynewrow.VALID_FROM = :lv_d;
end;
You set only the new row columns before Insert command executes over the target table.
You don't explicitly execute an INSERT command, just set new values for new row columns. That's all
I hope it helps
I am new to PLSQL in Oracle. When I am learning about triggers, I have read from this source https://www.techonthenet.com/oracle/triggers/before_insert.php which says that when I create a BEFORE INSERT Trigger in Oracle, the FOR EACH ROW is NOT always needed, hence the syntax is enclosed by square brackets [ ]. I have written this simple trigger:
CREATE OR REPLACE TRIGGER enroll_time
BEFORE INSERT
ON ENROLL
FOR EACH ROW
BEGIN
:new.addtime := sysdate;
END;
/
If I remove the FOR EACH ROW in the above, I actually get an error:
Error report -
ORA-04082: NEW or OLD references not allowed in table level triggers
04082. 00000 - "NEW or OLD references not allowed in table level triggers"
*Cause: The trigger is accessing "new" or "old" values in a table trigger.
*Action: Remove any new or old references.
From the error message, it seems like if I use :new.[column_name], then FOR EACH ROW must have to exist. Why is this? Is there any example that FOR EACH ROW is NOT needed in a BEFORE INSERT TRIGGER in Oracle?
Is there any example that FOR EACH ROW is NOT needed in a BEFORE INSERT TRIGGER in Oracle?
Simple example of statement level trigger:
CREATE TABLE test_table(col VARCHAR2(10));
CREATE OR REPLACE TRIGGER enroll_time
BEFORE INSERT
ON ENROLL
BEGIN
INSERT INTO test_table(col)
SELECT 1 FROM dual;
END;
/
I highly recommend to read about compound trigger to understand when each part is fired.
Basically, if you need to use :OLD or :NEW pseudotables, you need a row level trigger. An example of a statement level trigger would be inserting a record into a table when another table is effected.
I've created a trigger as follows:
create or replace trigger "PASSENGERS_BACKUP_T1"
after
insert or update or delete on "PASSENGERS"
for each row
begin
if :NEW."P_ID" is NOT null then
INSERT INTO PASSENGERS_BACKUP(
PB_ID,
PB_FIRST_NAME,
PB_LAST_NAME,
PB_STREET_ADDRESS1,
PB_STREET_ADDRESS2,
PB_CITY,
PB_STATE,
PB_POSTAL_CODE,
PB_EMAIL,
PB_PHONE_NUMBER1,
PB_PHONE_NUMBER2,
PB_URL,
PB_CREDIT_LIMIT,
PB_TAGS)
VALUES (
:new.P_ID,
:new.P_FIRST_NAME,
:new.P_LAST_NAME,
:new.P_STREET_ADDRESS1,
:new.P_STREET_ADDRESS2,
:new.P_CITY,
:new.P_STATE,
:new.P_POSTAL_CODE,
:new.P_EMAIL,
:new.PHONE_NUMBER1,
:new.PHONE_NUMBER1,
:new.URL,
:new.CREDIT_LIMIT,
:new.TAGS);
end if;
end;
now, when I update​ an existing row in "passengers" table as per the above trigger another new row is getting added in "passengers_backup" table instead I would like to update the existing row whenever an update is done in "passengers" table rows. As, well If I delete a row in "Passengers" table, if that row exists in 'Passengers_backup' table it should also get deleted. How can I acheive this?
Thanks in advance.
For solving your problem you need to use trigger with corresponding SQL statement for each action: insert, update, delete. As variant you can use something like this (Note, I left only two columns from your example for readability, so modify your trigger as you need):
create or replace trigger "PASSENGERS_BACKUP_TIUD"
after insert or update or delete on "PASSENGER"
for each row
begin
if inserting then
insert into "PASSENGER_BACKUP" (pb_id, pb_first_name)
values (:NEW.pb_id, :NEW.pb_first_name);
elsif updating then
update "PASSENGER_BACKUP"
set pb_id=:NEW.pb_id, pb_first_name=:NEW.pb_first_name
where pb_id=:NEW.pb_id;
elsif deleting then
delete from "PASSENGER_BACKUP"
where pb_id=:OLD.pb_id;
end if;
end;
Also you can see work of this trigger in action on SQL Fiddle.
My question is as follows:
User name = Admin
Whenever I perform an insert/update/delete operation on a table "a". I need to have a trigger that would insert the username in table "b"
Is that possible?
create or replace trigger audit_a_trg
before insert or update or delete on A
for each row
begin
insert into b values (user);
end;
/
Oracle's online documentation is pretty good. You can read the SQL reference here.
edit
user is a function which returns the name of the account which issues the DML. Find out more.