I have been bogged in this problem for quite a long time....Can anyone help me out?
Here is the thing I want to implement:
I have a table A, A has attributes: id, count, total. Here I am required to implement such a trigger: IF the count in table A is updated, the trigger will set the total to 1.
My initial code is like this:
CREATE OR REPLACE TRIGGER tri_A AFTER UPDATE OF count ON A
FOR EACH ROW
BEGIN
UPDATE A SET total = 1 WHERE id = :new.id;
END;
/
The problem with this is the mutating table. When the table is updated, the table will be locked. I searched for the answers, I tried pragma autonomous_transaction, but I got an invalid trigger specification error. And there are other comments saying that we should try to use a combination of triggers to do this....I can't figure out how to do this
Assuming id is the primary key, you don't want to UPDATE the table. You just want to set :new.total. You'll also need to do this in a BEFORE UPDATE trigger not an AFTER UPDATE trigger.
CREATE OR REPLACE TRIGGER tri_A
BEFORE UPDATE OF count ON A
FOR EACH ROW
BEGIN
:new.total := 1;
END;
Related
create or replace NONEDITIONABLE TRIGGER SumUpdate AFTER INSERT ON stavkaotpremnice FOR EACH ROW
declare pragma autonomous_transaction;
begin
UPDATE otpremnica a
set a.ukupno=
(SELECT SUM(ukupno)
FROM stavkaotpremnice
WHERE brojotpremnice =: new.brojotpremnice)
WHERE a.brojotpremnice = :new.brojotpremnice;
commit;
end;
This trigger is to sum values of a column called "ukupno" in table stavakaotpremnice then store it in another table otpremnica in a column also called "ukupno".
The trigger check if the id(brojotpremnice) is the same and make the sum.
Brojotpremnice is a foreign key from table otpremnica.
Does anyone know why it is totally ignoring the first entry?
If i put rows in stavkaotpremnica i just count the first entry.
This type of problem can be solved via incremental addition as follows:
UPDATE otpremnica a
set a.ukupno = a.ukupno + :new.ukupno
WHERE a.brojotpremnice = :new.brojotpremnice;
Also, please read about pragma autonomous_transaction. Why it is used? Intentional? If you have no idea, read it. (It separates the transaction)
I want to create an update trigger for a table. The trigger was created, but when I update the column finish, it say mutating table.
This is my code
CREATE OR REPLACE TRIGGER SET_COST BEFORE UPDATE OF finish ON PAY
FOR EACH ROW
BEGIN
UPDATE PAY
SET PAY.COST = (finish-start) * 20000
WHERE PAY.ID=:new.ID;
END;
This trigger gives me 'Mutating Table' error and so far I have been unable to fix it. Any Suggestion ? Thanks
First of all, you shouldn't be doing that at all. There's no use in storing values that are easily calculated whenever you need them.
As of your question: no UPDATE:
begin
:new.cost := (:new.finish - :new.start) * 20000;
end;
I am having an issue with a trigger. After I add the trigger to my database, when I try to insert a row that the trigger will act on, I get a mutating table error. I don't know how to avoid this. Would someone mind looking at this and tell me what I am doing wrong, and how to rewrite it?
CREATE OR REPLACE TRIGGER ORNG_INV_LINE_TOTAL_TRIGGER
FOR INSERT OR UPDATE ON ORNG_INV_LINE
COMPOUND TRIGGER
AFTER EACH ROW IS
BEGIN
UPDATE ORNG_INVOICE SET Inv_Amount = (SELECT SUM(ORNG_INV_LINE.Inv_Line_Total)
FROM ORNG_INV_LINE
WHERE ORNG_INVOICE.INV_Num = :NEW.INV_Num);
END AFTER EACH ROW;
END ORNG_INV_LINE_TOTAL_TRIGGER;
/
I'm not sure why it is triggering an error. I'm trying to do the action after the update. All I want to do is get the sum for all of the lines of all matching invoice numbers, and write that value in the INVOICE table. Thanks for the help.
Your trigger is written on the table ORNG_INV_LINE for insert or update and again you made a select on the same table while updating ORNG_INVOICE table so trigger is mutating,
to over come this you have to use statement level trigger instead of row level trigger .
i.e after each statement should be there in code instead of after each row.
This can help you.
Here is the solution...apparently everyone is busy with Thanksgiving. Hopefully this helps the next guy.
create or replace TRIGGER ORNG_INV_L_TTL_TRIG
AFTER INSERT OR UPDATE OR DELETE ON ORNG_INV_LINE
BEGIN
UPDATE ORNG_INVOICE SET Inv_Amount = (SELECT SUM(Inv_Line_Total)
FROM ORNG_INV_LINE
WHERE INV_Num = ORNG_INVOICE.INV_Num);
END ORNG_INV_L_TTL_TRIG;
/
I want to write a trigger for a table "TRANSACTION".When a new line is inserted, I want to trigger to update the field "TRANSACTIONID" to the maximum + 1 of all the previous records.
I on't know much about SQL. Can someone help me?
many thanks
This is a really bad idea for a multi-user environment, as it will serialise inserts into the table. The usual approach is to use an Oracle sequence:
create sequence transaction_seq;
create trigger transaction_bir before insert on transaction
for each row
begin
:new.id := transaction_seq.nextval;
end;
To write a trigger based solution that actually got the max current value plus 1, you would need to write a complex 3-trigger solution to avoid the "mutating table" issue. Or you could create a simpler solution using another table to hold the current maximum value like this:
create table transaction_max (current_max_id number);
insert into transaction_max values (0);
create trigger transaction_bir before insert on transaction
for each row
declare
l_current_max_id number;
begin
update transaction_max set current_max_id = current_max_id + 1
returning current_max_id into l_current_max_id;
:new.id := l_current_max_id;
end;
This will avoid the mutating table issue and will serialize (slow down) inserts, so I don't see any advantage of this over using a sequence.
CREATE TRIGGER trigger1 on TransactionTable
INSTEAD OF INSERT
AS
BEGIN
DECLARE #MaxTranId INT
SELECT
#MaxTranId = MAX(TransactionId)
FROM
TransactionTable
INSERT INTO TransactionTable
SELECT
#MaxTranId + 1 ,
RestOfYourInsertedColumnsHere ,
FROM
inserted
END
GO
i have two tables
Order(id, date, note)
and
Delivery(Id, Note, Date)
I want to create a trigger that updates the date in Delivery when the date is updated in Order.
I was thinking to do something like
CREATE OR REPLACE TRIGGER your_trigger_name
BEFORE UPDATE
ON Order
DECLARE
BEGIN
UPDATE Delivery set date = ??? where id = ???
END;
How do I get the date and row id?
thanks
How do i get the date and row id?
Assuming these are columns on your ORDER table called DELIVERY_DATE and ID your trigger should look something like this:
CREATE OR REPLACE TRIGGER your_trigger_name
BEFORE UPDATE ON Order
FOR EACH ROW
BEGIN
if :new.delivery_date != :old.delivery_date
then
UPDATE Delivery d
set d.delivery_date = :new.delivery_date
where d.order_id = :new.id;
end if;
END;
Note the FOR EACH ROW clause: that is necessary to reference values from individual rows. I have used an IF construct to test whether to execute the UPDATE on Delivery. If you have no other logic in your trigger you could write it like this...
CREATE OR REPLACE TRIGGER your_trigger_name
BEFORE UPDATE OF delivery_date ON Order
FOR EACH ROW
BEGIN
UPDATE Delivery d
set d.delivery_date = :new.delivery_date
where d.order_id = :new.id;
END;
I have answered the question you asked but, as an aside, I will point out that your data model is sub-optimal. A properly normalized design would hold DELIVERY_DATE on only one table: DELIVERY seems teh logical place for it.
Use the OLD and NEW bind variables. OLD references the row or column being updated before the change is made; NEW references it after the change.
CREATE OR REPLACE TRIGGER trig1
BEFORE UPDATE
ON order REFERENCING NEW AS new
FOR EACH ROW
BEGIN
UPDATE delivery
SET ddate = :new.ddate
WHERE id = :new.id;
END;
You can modify the REFERENCING clause to give your bind variables different names. You can include OLD as <name> too. Example:
CREATE OR REPLACE TRIGGER trig1
BEFORE UPDATE
ON order REFERENCING OLD AS old_values NEW AS new_values
...
If you don't want to change the default names of "old" and "new", you can leave out the REFERENCING clause completely.
There is an implicit new and old reference in the trigger in the form of:
REFERENCING OLD AS OLD NEW AS NEW
You can write to the :NEW value but not to the :OLD value.
UPDATE Delivery set date = :new.delivery_date where id = :new.id;
CREATE OR REPLACE TRIGGER "BUR_TABLENAME" BEFORE
UPDATE ON "TABLE" FOR EACH ROW
BEGIN
If :new.active_date is not null Then
:new.active_date := TRUNC(:new.active_date);
End If;
END;
Template:
CREATE OR REPLACE TRIGGER TRIGGER_NAME
BEFORE
UPDATE
ON TABLE_NAME
REFERENCING OLD AS OLD NEW AS NEW
FOR EACH ROW
DECLARE
V_VARIABLE NUMBER (1);
BEGIN
//Do Stuff;
null;
end;
Whenever there is a need for this kind of trigger, have a good look at your design. Is there really a need for a separate delivery record? Does an order really have more than 1 delivery ?
Triggers seem nice but they do tend to mess things up pretty quickly.