Maybe it's quite easy but I don't get ahead. The table B contains two fields: product_no NUMBER and product VARCHAR2. What the trigger should do is to insert a corresponding product description from BP-table in which you also have the fields product_no and product.
E.g. you enter 20 in B.product_no then it should be automatically entered the right product from BP-Table. Oracle version is 11g.
CREATE OR REPLACE TRIGGER A.trigger_on_B
AFTER INSERT OR UPDATE
ON A.B FOR EACH ROW
DECLARE
varProduct varchar(20);
BEGIN
SELECT bp.report_info
into varProduct
from bp,
B
where bp.product_no = B.product_no;
insert into B (product) values(varProduct) ;
exception
when others then NULL;
END;/
You can user pseudo records :new, :old, to make it work:
CREATE OR REPLACE TRIGGER A.trigger_on_B
AFTER INSERT OR UPDATE
ON A.B FOR EACH ROW
DECLARE
varProduct varchar(20);
BEGIN
SELECT bp.report_info
into varProduct
from bp
where bp.product_no = :new.product_no;
insert into B (product) values(varProduct) ;
exception
when others then NULL;
END;
Get rid of the line when others then NULL; this is unappropriated you can't hide any exceptions.
Get rid of your triggers, it is hard to maintenance code with logic in triggers. For more information check this article
Related
Im doing a college project on Oracle SQL and I keep getting the error "table (...) is mutating, trigger/function may not see it" when I try to update a table. My participateTeams table has 3 columns (eventName varchar(), teamId number, teamPlace number).
The Objective here is that when I update the teamPlace of a given team in an event, the place MUST be lower or equal than the number of participant teams in that same event.
My trigger is as follows:
Before update on participateTeams
for each row
Declare participants number;
Begin
select count(*) into participants from participateteams where :New.eventName = participateteams.eventName;
if(:NEW.teamplace>participants) then
RAISE_APPLICATION_ERROR(-20250,'O lugar da equipa é inválido');
end if;
End;
/
From what I've researched it's because I'm trying to read the same table that called the trigger.
I have also have tried exporting the select part of the code into a function, but the issue persists.
The participants in the event are the teams theirselves and not the individuals that form those same teams. Example: If team A, team B and team C participate in an event E, the count for that same event E should be 3.
Any tips? Thank you.
The mutating table error is just a pain. And what you are trying to do is rather tricky. Here is one approach:
Add a column to teams with the count of participants.
Maintain this column with insert/update, and delete triggers on participateteams.
Write a user-defined function to fetch the count for a given team.
Add a check constraint in participateteams using the user-defined function.
The logically correct trigger for what you want to achieve is this :-
CREATE OR REPLACE TRIGGER TRIG_CHK
AFTER INSERT OR UPDATE OF teamPlace ON participateteams
FOR EACH ROW
DECLARE
participants NUMBER;
BEGIN
select count(*) into participants from participateteams where :New.eventName =
participateteams.eventName;
if(:NEW.teamplace>participants) then
RAISE_APPLICATION_ERROR(-20250,'O lugar da equipa é inválido');
end if;
End;
update participateteams set teamPlace = 2 where eventName = 'B';
But when it gives Mutating table error when trying to update table participateteams,to solve this tricky situation , what I did is :-
step1 :Declare the table columns needed in a package header
CREATE OR REPLACE PACKAGE PKG_TEAMS AS
v_eventName participateteams.eventName%type;
v_teamPlace participateteams.teamPlace%type;
end;
step2 : Initialize the variables in a row level trigger
CREATE OR REPLACE TRIGGER TRG_row
AFTER INSERT OR UPDATE OF teamPlace
ON participateteams
FOR EACH ROW
BEGIN
PKG_TEAMS.v_eventName := :NEW.eventName;
PKG_TEAMS.v_teamPlace := :NEW.teamPlace;
END;
step3 :Now ,rather than using :NEW pseudo columns, using globally initialized variables
CREATE OR REPLACE TRIGGER TRG_stmt
AFTER INSERT OR UPDATE OF teamPlace ON participateteams
DECLARE
v_participants NUMBER;
BEGIN
SELECT COUNT(*) INTO v_participants FROM participateteams
WHERE eventName = PKG_TEAMS.v_eventName;
if(PKG_TEAMS.v_teamPlace>v_participants) then
RAISE_APPLICATION_ERROR(-20250,'CANNOT UPDATE,AGAINST RULES');
end if;
End;
I have a table COMMANDE and a table REGROUPE. I have that function:
CREATE OR REPLACE PROCEDURE multiplicateur(a NUMBER, taxes NUMBER, c OUT NUMBER)
IS
BEGIN
c := a * taxes ;
END multiplicateur;
/
I'm trying to make a trigger using that founction to update a total price with taxes from a command that can contain more than one item. I tried this but it doesn't want to work:
create or replace TRIGGER MAJ_PRIX_COMMANDE
AFTER INSERT OR UPDATE OR DELETE ON REGROUPE
FOR EACH ROW
DECLARE
resultat NUMBER;
BEGIN
UPDATE COMMANDE
SET COMMANDE.prixTotal = multiplicateur((CAST((SELECT SUM(prixRegroupe)FROM REGROUPE WHERE REGROUPE.numCommande = :NEW.numCommande)AS NUMBER)),1.15,resultat)
WHERE COMMANDE.numCommande = :NEW.numCommande;
END;
Can someone help me?
How about this? I sent this from my iPhone; this code hasn't been tested.
create or replace TRIGGER MAJ_PRIX_COMMANDE
AFTER INSERT OR UPDATE OR DELETE ON REGROUPE
FOR EACH ROW
DECLARE
resultat NUMBER;
l_groupe NUMBER; --will store sum based on numCommande
BEGIN
--retrieve sum of prixRegroupe
SELECT SUM(r.prixRegroupe)
INTO l_groupe
FROM regroupe r
WHERE r.numCommande = :NEW.numCommande;
--call procedure and pass the sum of priRegroupe
multiplicateur(l_groupe, 1.15, resultat);
--use precedures out argument to update commande
UPDATE COMMANDE c
SET c.prixTotal = resultat
WHERE c.numCommande = :NEW.numCommande;
END;
This code won't work. It will result in a mutating trigger error. Within a trigger you cannot query or modify the same table that the trigger is based on until after the trigger has completed execution.
ORA-04091: table name is mutating, trigger/function may not see it
Your problem right now is that you're querying the regroupe table while the trigger is trying to insert/update the same table. This cannot be accomplished.
You'll need to find a way to get the sum of the prixRegroup column some other way. It's late if I think of anything I'll respond tomorrow.
I want a trigger that updates the value of a column, but I just want to update a small set of rows that depends of the values of the inserted row.
My trigger is:
CREATE OR REPLACE TRIGGER example
AFTER INSERT ON table1
FOR EACH ROW
BEGIN
UPDATE table1 t
SET column2 = 3
WHERE t.column1 = :new.column1;
END;
/
But as I using FOR EACH ROW I have a problem when I try it, I get the mutating table runtime error.
Other option is not to set the FOR EACH ROW, but if I do this, I dont know the inserted "column1" for comparing (or I dont know how to known it).
What can I do for UPDATING a set of rows that depends of the last inserted row?
I am using Oracle 9.
You should avoid the DML statements on the same table as defined in a trigger. Use before DML to change values of the current table.
create or replace trigger example
before insert on table1
for each row
begin
:new.column2 := 3;
end;
/
You can modify the same table with pragma autonomous_transaction:
create or replace trigger example
after insert on table1 for each row
declare
procedure setValues(key number) is
pragma autonomous_transaction;
begin
update table1 t
set column2 = 3
where t.column1 = key
;
end setValues;
begin
setValues(:new.column1);
end;
/
But I suggest you follow #GordonLinoff answere to your question - it's a bad idea to modify the same table in the trigger body.
See also here
If you need to update multiple rows in table1 when you are updating one row, then you would seem to have a problem with the data model.
This need suggests that you need a separate table with one row per column1. You can then fetch the value in that table using join. The trigger will then be updating another table, so there will be no mutation problem.
`create table A
(
a INTEGER,
b CHAR(10)
);
create table B
(
b CHAR (10),
d INTEGER
);
create trigger trig1
AFTER INSERT ON A
REFERENCING NEW AS newROW
FOR EACH ROW
when(newROW.a<=10)
BEGIN
INSERT into B values(:newROW.b,:newROW.a);
END trig1;
insert into A values(11,'Gananjay');
insert into A values(5,'Hritik');
select * from A;
select * from B;`
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.
I want to insert the same record on both tables at the same time.
I.e., while I insert a record for the first table, this same record also is inserted in the second table using a trigger.
Do you have any experience/advice in this process ?
if you're using stored procedures you can easily manage this
CREATE PROCEDURE sp_Insert
#Value varchar(10)
AS
insert into table1 (...,...) values (#value,...)
insert into table2 (...,...) values (#value,...)
I would suggest using Erik's method over a trigger. Triggers tend to cause performance issues, and a lot of times, you forget that the trigger exists, and get unexpected behavior. If you do want to use a trigger however, it will work. here is an example:
CREATE TRIGGER trgTest ON Test
FOR INSERT
AS
INSERT Test2
(Id, value)
SELECT Id, Value
FROM Inserted
Can Use Cursor Concept!
CREATE OR REPLACE TRIGGER bi_order
BEFORE INSERT
ON ord
REFERENCING OLD AS OLD NEW AS NEW
FOR EACH ROW
WHEN (NEW.payment_type = 'CREDIT')
DECLARE
CURSOR cur_check_customer IS
SELECT 'x'
FROM customer
WHERE customer_id = :NEW.customer_id
AND credit_rating = 'POOR';
lv_temp_txt VARCHAR2(1);
lv_poor_credit_excep EXCEPTION;
BEGIN
OPEN cur_check_customer;
FETCH cur_check_customer INTO lv_temp_txt;
IF (cur_check_customer%FOUND) THEN
CLOSE cur_check_customer;
RAISE lv_poor_credit_excep;
ELSE
CLOSE cur_check_customer;
END IF;
EXCEPTION
WHEN lv_poor_credit_excep THEN
RAISE_APPLICATION_ERROR(-20111, 'Cannot process CREDIT ' ||
'order for a customer with a POOR credit rating.');
WHEN OTHERS THEN
RAISE_APPLICATION_ERROR(-20122, 'Unhandled error occurred in' ||
' BI_ORDER trigger for order#:' || TO_CHAR(:NEW.ORDER_ID));
END bi_order;