I have two tables
Parent(id, name, occupation)
Child(id, name, gender,parent_id, parent_name, parent_occupation)
Now to insert value in child i'll run chi query
insert into Child(id,name,gender,parent_id) values(10,'XYZ','Male',15);
So now my requirement is when this insert query is executed a trigger will run and get name and occupation from parent table for id 15 (parent_id of the Child record) and add it to the newly inserted row in fields parent_name and parent_occupation respectively.
I am using Oracle 11g as my database.
You want something akin to this (though you'll need to add code to handle the exception):
CREATE OR REPLACE
TRIGGER ai_child_tg
AFTER INSERT ON child
REFERENCING NEW AS NEW OLD AS OLD
FOR EACH ROW
BEGIN
SELECT name,
occupation
INTO :NEW.parent_name,
:NEW.parent_occupation
FROM parent
WHERE id = :NEW.parent_id;
EXCEPTION
WHEN no_data_found
THEN
<handle_your_exception_>
END ai_child_tg;
However, if your CHILD table is really a relational child to your PARENT table and there is a FK relationship in place (via the CHILD.PARENT_ID column) then storing the PARENT_NAME and PARENT_OCCUPATION columns in the CHILD table is logically redundant.
I'd query why you have those two columns in the CHILD table at all.
Hope it helps...
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;
/
A sequence is used to generate id for a customer table and then using trigger to populate the id column as a varchar value.
The trigger is
CREATE OR REPLACE TRIGGER USER_ID_TRIGGER
before insert on CUSTOMER
REFERENCING NEW AS New OLD AS Old
for each row
begin
-- :new.user_id := 'CUST' || :new.user_id ;
select 'CUST' || SEQ_CUSTOMER_ID.nextval into :new.user_id from dual;
end USER_ID_TRIGGER;
So, each insert in the column is like 'CUST1', 'CUST3', etc.
The trigger can't be changed.
I am using hibernate save(customer) method to save customer objects in the db. Problem is the return id value I am getting is (as expected) different from the one that is ultimately saved in the table.
For example, if the id populated in the column is 'CUST19', the hibernate code returns 18.
My question is, if the code returns a value of 210, will it be safe for me to assume that the populated value is CUST211?
I have two back-end systems (the old one and the new one) that shares an Oracle DB.
In the older system, to save customers data, there are two tables
customers_A
ID NAME ETC
1 PETE ....
customers_B
ID NAME ETC
1 JOSH ...
2 ROSS ...
In the new system I've created a new table called All_Costumer, to join those tables.
This new table contains customer ID's of type A and B respectively.
All_Customers
ID ID_CUSTOMER_A ID_CUSTOMER_B
A19E----D2B0 1 null
A19E----D2B1 null 1
A19E----D2B2 null 2
So, when the new system creates a new customer of type A, data are inserted on customer_A and All_Customers tables, with customer of type B as well.
Currently, the old system is working too, and when a new customer of type A is created, data is inserted only on customer_A table, but I need that data in All_Customers too.
To solve this, I've created a TRIGGER with a MERGE INTO statement inside, to insert a row in All_Customers if doesn't exist on this table (when a new customer of type A are created by the older system)
CREATE OR REPLACE TRIGGER customers_trg
AFTER INSERT
ON customer_A
FOR EACH ROW
DECLARE
variables that doesn't matters
BEGIN
MERGE INTO all_customers
USING (SELECT :new.id id FROM customer_A where id = :new.id) customer
ON (all_customers.id_customer_a = customer.id)
WHEN NOT MATCHED THEN
INSERT (id, id_customer_a)
VALUES (SYS_GUID(), :new.id, null);
COMMIT;
END;
But when I try to create a new customer from the older system, I get this error:
ORA-04091: table **customer_A** is mutating, trigger/function may not see it
Any idea to solve this?
I've tried adding PRAGMA AUTONOMOUS_TRANSACTION; on DECLARE section, but didn't work.
Note: I can't modify the old system
The immediate issue is that you're querying table_a in a trigger against that table; but you don't need to. Your merge query
SELECT :new.id id FROM customer_A where id = :new.id
can simply do
SELECT :new.id id FROM dual
i.e. the clause becomes:
...
USING (SELECT :new.id id FROM dual) customer
ON (all_customers.id_customer_a = customer.id)
...
You also can't commit in a trigger - unless it's autonomous, which this shouldn't be. You said you'd tried that, but it breaks if the insert is rolled back, since the merged row will still exist. So hopefully that commit is just a hang-over from trying and rejecting that approach.
But it works in this db<>fiddle, anyway.
If you weren't adding the GUID you could get the same effect with a view:
create or replace view all_customers (id_customer_a, id_customer_b) as
select id, null from customers_a
union all
select null, id from customers_b;
db<>fiddle
I want to create a trigger wherein the child table pulls all the exisiting records from parent table.
I have created child tables referencing the parent table primary key as foreign key in new table
CREATE OR REPLACE TRIGGER trigger name
AFTER INSERT ON table_name(parent_table)
FOR EACH ROW
BEGIN
insert statement for child table;
END;
Above trigger is created for records which will be inserting post to child table creation, I would like to push all old records (which were present prior to child table creation) to the new child table. Will triggers help in pulling all the old records ?
Obviously NO!!
The trigger will start inserting records to the child table from the parent table post creation of trigger. Records inserted into parent table prior to trigger creation need to be inserted manually.
If you want to pull all records before the creation of trigger into child table from parent table then you need to write one-time INSERT query as following:
INSERT INTO CHILD_TABLE
SELECT * FROM PARENT_TABLE P
WHERE NOT EXISTS (SELECT 1 FROM CHILD_TABLE C WHERE P.PK = C.FK);
-- OR --
INSERT INTO CHILD_TABLE
SELECT * FROM PARENT_TABLE P
WHERE P.PK IN
(SELECT PK FROM PARENT_TABLE
MINUS
SELECT FK FROM CHILD_TABLE
)
Cheers!!
Using Oracle, we have 2 tables - Parent and Child.
We have the ID column as GUID in Parent table and this value is being created by a trigger before insert.
Now while inserting records in same transaction, I need to
- First add a record to Parent table, then
- Use the new GUID created in trigger to add records to child table
How do I retrieve this new GUID for subsequent inserts?
you can use returning into clause of insert statement
INSERT INTO parent VALUES (col1, ...)
RETURNING <your id column > INTO < variable>;
insert into child (parent_id) values (< variable>);