Can I create an AFTER TRIGGER on a table and using that table in my SELECT query without getting mutating table error?
Example to a query I want to use.
This query will update number of times a certain status name is showing up in alert life cycle:
CREATE OR REPLACE TRIGGER COUNT_STEP
AFTER INSERT
ON STEPS
FOR EACH ROW
DECLARE
V_COUNT_SETP VARCHAR (10000);
BEGIN
SELECT COUNT (STATUS_NAME)
INTO V_COUNT_SETP
FROM (SELECT A.ALERT_ID, S.STATUS_NAME
FROM ALERTS A, ALERT_STATUSES S, STEPS ST
WHERE :NEW.ALERT_INTERNAL_ID = A.ALERT_INTERNAL_ID
AND ST.ALERT_STATUS_INTERNAL_ID = S.STATUS_INTERNAL_ID
AND S.STATUS_NAME IN ('Auto Escalate'))
GROUP BY ALERT_ID;
UPDATE ALERTS A
SET A.COUNT = V_COUNT_ESC
WHERE A.ALERT_INTERNAL_ID = :NEW.ALERT_INTERNAL_ID;
END;
/
The table I'm inserting a record to is also needed for counting the number of step occurrences since it's stores the alert id and all the steps id it had.
You need to be a bit more clearer in your questions. But, from what i understood, you need to create a trigger on a table, and perform a select for that same table. That gives you a mutanting table error. To bypass that, you need to perform a compound trigger on that table. Something like this:
create or replace trigger emp_ct
for insert on employees compound trigger
v_count number; -- Add variable here
before statement is
begin
-- PERFORM YOUR SELECT AND SEND TO A VARIABLE
end before statement;
after each row is
begin
-- DO WANT YOU WANTED TO DO. USE THE VARIABLE
end after each row;
end;
basically, with a compound trigger, you can capture every trigger event. By doing that, allows to query the table you're capturing.
Related
Good morning, I am trying to audit two tables, and I have investigated that it cannot be done, therefore I explain what I wanted to do:
I have two tables (Participante, Actividad) which are joined by a third table (Part_Actividad)
I want to audit the Participants table, but in the same way I need the Id of the activity to know in which activity the data of a participant is changed.
Ideas I had
Create a trigger like the following
CREATE OR REPLACE TRIGGER Tri_Auditoria
AFTER INSERT ON Participante
FOR EACH ROW
DECLARE
v_Participante_ID Participante.Participante_ID%TYPE;
v_Actividad_ID Part_Actividad.Actividad_ID%TYPE;
BEGIN
SELECT participante_ID INTO v_Participante_ID
FROM Participante;
SELECT Actividad_ID INTO v_Actividad_ID
FROM Part_Actividad
WHERE PartAct_ID = v_Participante_ID;
INSERT INTO Auditoria(Auditoria_ID, Actividad_ID, Participante_ID, TipPart_ID_Ant, Part_P_Nombre_Ant, Part_P_Apell_Ant, Part_Cedula_Ant, Part_Genero_ant, Part_FNaci_Ant, Aud_Operacion, Usuario_Modificador, Fecha_Modificacion)
VALUES (sec_Auditoria.nextval, v_Actividad_ID, :new.Participante_ID,:new.TipPart_ID,:new.Part_P_Nom,:new.Part_P_Apell,:new.Part_Cedula,:new.Part_Genero,:new.Part_FNaci,'I',USER,sysdate);
END Tri_Auditoria;
/
Result:
When I insert data into the participante table, it is not inserted and it sends a trigger error.
Mutating table error, isn't it? That's because you're selecting from the same table which caused trigger to fire, and that's not allowed.
Anyway, you shouldn't do that because you have that value in disposal - just reference it using the :new pseudorecord, such as
CREATE OR REPLACE TRIGGER Tri_Auditoria
AFTER INSERT ON Participante
FOR EACH ROW
DECLARE
v_Actividad_ID Part_Actividad.Actividad_ID%TYPE;
BEGIN
SELECT Actividad_ID
INTO v_Actividad_ID
FROM Part_Actividad
WHERE PartAct_ID = :new.participante_ID; --> this
INSERT INTO Auditoria
(Auditoria_ID, Actividad_ID, Participante_ID,
TipPart_ID_Ant, Part_P_Nombre_Ant, Part_P_Apell_Ant,
Part_Cedula_Ant, Part_Genero_ant, Part_FNaci_Ant,
Aud_Operacion, Usuario_Modificador, Fecha_Modificacion)
VALUES (sec_Auditoria.nextval, v_Actividad_ID, :new.Participante_ID,
:new.TipPart_ID,:new.Part_P_Nom,:new.Part_P_Apell,
:new.Part_Cedula,:new.Part_Genero,:new.Part_FNaci,
'I',USER,sysdate);
END Tri_Auditoria;
/
I am trying to create a row level trigger to delete a row if a value in the row is being made NULL. My business parameters state that if a value is being made null, then the row must be deleted. Also, I cannot use a global variable.
BEGIN
IF :NEW.EXHIBIT_ID IS NULL THEN
DELETE SHOWING
WHERE EXHIBIT_ID = :OLD.EXHIBIT_ID;
END IF;
I get the following errors:
ORA-04091: table ISA722.SHOWING is mutating, trigger/function may not see it
ORA-06512: at "ISA722.TRG_EXPAINT", line 7
ORA-04088: error during execution of trigger 'ISA722.TRG_EXPAINT'
When executing this query:
UPDATE SHOWING
SET EXHIBIT_ID = NULL
WHERE PAINT_ID = 5104
As already indicated this is a terrible idea/design. Triggers are very poor methods for enforcing business rules. These should be enforced in the application or better (IMO) by a stored procedure called by the application. In this case not only is it a bad idea, but it cannot be implemented as desired. Within a trigger Oracle does not permit accessing the table the trigger fired was fired on. That is what mutating indicates. Think of trying to debug this or resolve a problem a week later. Nevertheless this non-sense can be accomplished by creating view and processing against it instead of the table.
-- setup
create table showing (exhibit_id integer, exhibit_name varchar2(50));
create view show as select * from showing;
-- trigger on VIEW
create or replace trigger show_iiur
instead of insert or update on show
for each row
begin
merge into showing
using (select :new.exhibit_id new_eid
, :old.exhibit_id old_eid
, :new.exhibit_name new_ename
from dual
) on (exhibit_id = old_eid)
when matched then
update set exhibit_name = new_ename
delete where new_eid is null
when not matched then
insert (exhibit_id, exhibit_name)
values (:new.exhibit_id, :new.exhibit_name);
end ;
-- test data
insert into show(exhibit_id, exhibit_name)
select 1,'abc' from dual union all
select 2,'def' from dual union all
select 3,'ghi' from dual;
-- 3 rows inserted
select * from show;
--- test
update show
set exhibit_name = 'XyZ'
where exhibit_id = 3;
-- 1 row updated
-- Now for the requested action. Turn the UPDATE into a DELETE
update show
set exhibit_id = null
where exhibit_name = 'def';
-- 1 row updated
select * from show;
-- table and view are the same (expect o rows)
select * from show MINUS select * from showing
UNION ALL
select * from showing MINUS select * from show;
Again this is a bad option yet you can do. But just because you can doesn't mean you should. Or that you'll be happy with the result. Good Luck.
You have written a trigger that fires after or before a row change. This is in the middle of an execution. You cannot delete a row from the same table in that moment.
So you must write an after statement trigger instead that only fires when the whole statement has run.
create or replace trigger mytrigger
after update of exhibit_id on showing
begin
delete from showing where exhibit_id is null;
end mytrigger;
Demo: https://dbfiddle.uk/?rdbms=oracle_18&fiddle=dd5ade700d49daf14f4cdc71aed48e17
What you can do is create an extra column like is_to_be_deleted in the same table, and do this:
UPDATE SHOWING
SET EXHIBIT_ID = NULL, is_to_be_deleted = 'Y'
WHERE PAINT_ID = 5104;
You can use this parameter to implement your business logic of not showing the null details.
And later you can schedule a batch delete on that table to clean up these rows (or maybe archive it).
Benefit: you can avoid an extra unnecessary trigger on that table.
Nobody, will suggest you to use trigger to do this type of delete as it is expensive.
I am attempting to follow the instructions at Mutating Table Compound Trigger to update a parent table based on the id of a child table and avoid a mutating table error.
I need to obtain the parent id (BLATranscriptId) of the current record in the BLATChildren table and then after the update of the child record completes, I need to extract the current count that matches my criteria and perform an update on the parent table BLATranscript.
THIS ERROR HAS BEEN SOLVED - I'm getting an error that my bind variable "transcriptID" is bad in the "AFTER EACH ROW" portion of my code. I've verify that the BLATChildren.BLATranscriptId exists and is spelled correctly. Solution was to change AFTER EACH ROW to AFTER STATEMENT.
NEW ISSUE - Trigger is updating every record in the parent table, not just the matching parent record.
Any help would be greatly appreciated. Thank you.
CREATE OR REPLACE TRIGGER transcript_after_update
FOR UPDATE of enrollmentStatus,completionDate on blatChildren
COMPOUND TRIGGER
transcriptID number:=0;
BEFORE EACH ROW IS
BEGIN
transcriptID := :new.blaTranscriptid;
END BEFORE EACH ROW;
AFTER STATEMENT IS
BEGIN
update BLATranscript SET (enrollmentStatus, completionDate) = (select 'C',sysdate from dual)
where id in (select blat.id from BLATranscript blat
inner join BlendedActivity bla on blat.blendedactivityid=bla.id
where blat.id=transcriptID and minCompletion<=(
select count(countForCompletion) as total from blatChildren blac
inner join BlendedActivityMembership bam on blac.childActivityId=bam.childActivityId
where completionDate>=sysdate-acceptPrevWork
and blat.id=transcriptID
and blac.enrollmentStatus='C'));
END AFTER STATEMENT;
END;
/
You need for each row part to collect :new.blaTranscriptid int PL/SQL table
and after statement part that will perform update using this PL/SQL table.
Like:
CREATE OR REPLACE TRIGGER transcript_after_update
FOR UPDATE of enrollmentStatus,completionDate on blatChildren
COMPOUND TRIGGER
TYPE transcriptIDs_t IS TABLE OF blatChildren.blaTranscriptid%TYPE;
transcriptID transcriptIDs_t := transcriptIDs_t();
BEFORE EACH ROW IS
BEGIN
transcriptID.extend;
transcriptID(transcriptID.count) := :new.blaTranscriptid;
END BEFORE EACH ROW;
AFTER STATEMENT IS
BEGIN
FOR i IN 1..transcriptID.COUNT
LOOP
update BLATranscript SET (enrollmentStatus, completionDate) = (select 'C',sysdate from dual)
where id in (select blat.id from BLATranscript blat
inner join BlendedActivity bla on blat.blendedactivityid=bla.id
where blat.id = transcriptID(i) and minCompletion<=(
select count(countForCompletion) as total from blatChildren blac
inner join BlendedActivityMembership bam on blac.childActivityId=bam.childActivityId
where completionDate>=sysdate-acceptPrevWork
and blat.id=transcriptID(i)
and blac.enrollmentStatus='C'));
END LOOP;
END AFTER STATEMENT;
END;
/
I am making a web application which uses a database in which I have a field I_ID which i want to automatically increment like I0 then I1 then I2 and so on with each record insertion in the database.
To achieve it I made a trigger for this table.But its not working fine.What can be the reason.Please help
My Trigger T1:
CREATE OR REPLACE TRIGGER "T1"
before
insert on "TBINDIVIDUAL"
for each row
declare
x varchar2(10);
mx varchar2(13);
mx2 varchar2(13);
y number(3);
begin
x:=:new.I_ID;
mx:=substr(x,1,1);
select max(I_ID) into mx2 from tbindividual where I_ID like mx||'%';
y:=to_number(substr(mx2,2));
:new.I_ID:=mx||to_char(y+1);
end t1;
/
EDITED :
As i do by answer
CREATE OR REPLACE TRIGGER "TBINDIVIDUAL_T1"
BEFORE
insert on "TBINDIVIDUAL"
for each row
begin
:new.I_ID = SEQ1.nextval;
end;
/
But it give two errors
Encountered the symbol "=" when expecting one of the following: := . ( # % ; indicator
Encountered the symbol "END"
Please help
So Oracle is not SQL Server...
if you want to get unique ID's, you need to populate them from a sequence.
for creating a sequence use:
create sequence myseq;
and in your code use (depends on the version):
:new.I_ID := myseq.nextval;
or
select myseq.nextval into :new.I_ID from dual;
the problem your code doesn't work is what :new and :old means...
I would recommend you reading about their meaning...
Hope I've been helpful...
Because of the discussion in the comments - here is a full example:
for this table:
CREATE TABLE test (A number);
to add a unique, sequential ID you need to first create a sequence:
CREATE SEQUENCE myseq;
and a trigger:
CREATE OR REPLACE TRIGGER "T1"
before
insert on "test"
for each row
begin
:new.I_ID := myseq.nextval;
end t1;
/
by the way - I would recommend to check before substituting :new.I_ID, if it is null or not, cause sometimes in upgrades people add a unique ID from an external resource.. (such as them getting a unique number from the sequence themselves...)
you can read more about sequences here:
http://docs.oracle.com/cd/B28359_01/server.111/b28286/statements_6015.htm#SQLRF01314
sorry for the way the code is displayed.. need to learn how to write code here...
One more thing - In Oracle - you cannot create such a PL/SQL to increase existing counter without locks.
Concurrent queries might run the first query in the PL/SQL simultaneously, which means multiple sessions will get the same I_ID.
Also notice that in your code you queried the max on varchar, which is not the same as max on number...
Adding concatenated text is unrelated to the unique ID. In your case it will look like:
:new.I_ID = substr(:new.I_ID,1,1)||to_char(myseq.nextval);
assuming x is being inputted with the char you want..
I am having problems with this code below, which is a trigger used in Oracle SQL:
CREATE OR REPLACE TRIGGER TRG_TUTOR_BLOCK
BEFORE INSERT OR UPDATE ON tutors
FOR EACH ROW
DECLARE
BEGIN
IF :new.tutorName = :old.tutorName
THEN
RAISE_APPLICATION_ERROR(-20101, 'A tutor with the same name currently exists.');
ROLLBACK;
END IF;
END;
/
This trigger is used to prevent users from entering the same tutor name at different records.
After I insert two records with the same tutorname, the trigger does not block me from inserting it. Is there anyone can tell me what are the problems with this coding? Here are the sample format and insert values:
INSERT INTO tutors VALUES (tutorID, tutorName tutorPhone, tutorAddress, tutorRoom, loginID);
INSERT INTO tutors VALUES ('13SAS01273', 'Tian Wei Hao', '019-8611123','No91, Jalan Wangsa Mega 2, 53100 KL', 'A302', 'TianWH');
Trigger in Kamil's example will throw ORA-04091, you can see this with your own eyes here. ROLLBACK in a trigger is unnecessary, it runs implicitly when a trigger makes a statement to fail.
You can prohibit any DML on table by altering it with read only clause:
alter table tutors read only;
At last, integrity should be declarated with integrity constraints and not with triggers.
Good luck!
You don't need a trigger for this in Oracle.
You can do it with an "unique index" on the tutorName column (see http://docs.oracle.com/cd/B28359_01/server.111/b28310/indexes003.htm#i1106547).
Note: about your trigger, it fails on checking for another record with the same tutorName because it's not scanning the tutors table for another record with the same tutorName, it's just comparing the tutorName values of the row you are creating (in this case, old.tutorName is just NULL, because the row doesn't exist yet).
Check the case in yours trigger body
IF :new.tutorName = :old.tutorName
It returns true only if 'tutorName' value is the same in new and old record. When you'll trying to updat some value you'll get
IF 'someTutorName' = 'someTutorName'
which will return TRUE.
Inserting row cannot fire this rule because you're trying to compare something like that:
'someTutorName' = NULL
This case always returns FALSE.
Try to use something like that
CREATE OR REPLACE TRIGGER TRG_TUTOR_BLOCK
BEFORE INSERT OR UPDATE ON tutors
FOR EACH ROW
DECLARE
rowsCount INTEGER;
BEGIN
SELECT COUNT(*) FROM tutors WHERE tutorName is :new.tutorName INTO rowsCount;
IF rowsCount > 0
THEN
RAISE_APPLICATION_ERROR(-20101, 'A tutor with the same name currently exists.');
ROLLBACK;
END IF;
END;
/
But the best solution is the one mentioned by friol - use unique index by executing SQL like this
ALTER TABLE tutors
ADD CONSTRAINT UNIQUE_TUTOR_NAME UNIQUE (tutorName);
If you wanna completely ignore recording a row to a table you can follow these steps
rename table to something else and create a view with the same name and create an instead of trigger.
create table usermessages (id number(10) not null)
GO
alter table usermessages rename to xusermessages
GO
create or replace view usermessages as (select * from xusermessages)
GO
create or replace trigger usermessages_instead_of_trg
instead of insert or update on usermessages
for each row
begin
Null ;
end ;
GO
insert into usermessages(123)
Live test available here below
http://sqlfiddle.com/#!4/ad6bc/2