Create ORACLE TRIGGER which (INSERT OR UPDATE) in TABLE1 whenever a new INSERT is done in TABLE2

oracletrigger

i'm trying to create a TRIGGER for my Oracle database.
I Have 2 tables in it(table1 , table2)
Table 1 has 3 columns (id, name, value). id can be non unique here
Table 2 has 2 columns ( id, concat) id is unique here

What i want to do, is, every time a new row is inserted in Table 1., the trigger must Update the concat value of Table 2 which is a concate of name and values of all row where table1.id = table2.id

At the moment i think about this trigger, but i dont want to break anything in my db, so any advice would be great before testing 🙂


CREATE TRIGGER creation
AFTER INSERT  ON table1 ac
FOR EACH ROW
BEGIN 
UPDATE table2
SET concat= CONCAT(' ',CONCAT(ac.NAME, CONCAT('=',ac.VALUE)))
WHERE 
table1.id = table2.id 
END

Thx a lot

Best Answer

Try something like this. It also accounts for situations in which "id" didn't previously exist. Note: I used "concat_col" as the "concat" column name; @nbk is right - you shouldn't have column names that match pre-defined function names.

CREATE OR REPLACE TRIGGER TRIGGER1 
AFTER INSERT ON TABLE1 
REFERENCING OLD AS OLD NEW AS NEW 
FOR EACH ROW
BEGIN
   merge into table2
   using (select :new.id l_id from dual) d on (table2.id = d.l_id)
   when matched then   
      update set concat_col = concat_col || ' ' || :new.name || '=' || :new.value
   when not matched then
      insert (id, concat_col) values (:new.id, :new.name || '=' || :new.value);
END;
/

Related Solutions

Trigger or check constraint insert values based upon existence of others

If you query the table you're inserting into inside a trigger on that same table, you are likely to get "ORA-04091: table name is mutating, trigger/function may not see it." error. Check constraints cannot contain subqueries. Therefore your best option is to encapsulate logic for inserting data into a stored procedure and use that procedure instead of direct inserts.

I can assist you with writing the procedure, however, it seems to me that you have a logical flaw in your data model. Your example data shows that my_id is not a unique key for the table but rather that many rows may share the same value for my_id. So if one row with my_id = 1 has field_2 set to some value and for some other row field_2 is null, what is to be done? Don't you have a primary key in your table?

Anyways, if you want literally what you wrote in your post, you could do with something like

create or replace procedure my_practice_table_insert(p_my_id in number, p_field_2 in varchar2, p_field_3 in varchar2)
is
    l_cnt number;
begin
    if p_field_2 is null then
        select count(*) into l_cnt from my_practice_table where my_id = p_my_id and field_2 is not null;
    else
        select count(*) into l_cnt from my_practice_table where my_id = p_my_id and field_2 is null;
    end if;

    if l_cnt = 0 then
        insert into my_practice_table(my_id, field_2, field_3) values(p_my_id, p_field_2, p_field_3);
    end if;
end;

I didn't actually try out the procedure so it may have slight errors, but that's the general form it could take.

How to commit transaction on an after update event trigger

Why do you expect B to be updated, when you inserted a row with a different id? Actually, your INSERT ALL does not insert anything into B.

The above works fine after fixing your trigger and sample data:

create or replace trigger updB  
after update on B  
for each row  
declare  
v varchar2(5);  
begin  
  v := :new.val;
end;  
/

This is how you reference the new val in the trigger, not with a select. Your original trigger would run into the infamous ORA-04091 "table is mutating" error.

SQL> insert all into A values ('a', 'false') into b values ('a', 'false') select * from dual;

2 rows created.

SQL> commit;

Commit complete.

SQL> update A set val = 'true';
Cek cek: false

1 row updated.

SQL> commit;

Commit complete.

SQL> select * from a;

ID         VAL
---------- ----------
a          true

SQL> select * from b;

ID         VAL
---------- ----------
a          true

For the output:

Your updA trigger runs in an autonomous transaction. When you select val from A, your original update is still not finished (commited), you will see the old value. Fixing your trigger for A:

create or replace trigger updA  
after update on A  
for each row  
declare  
pragma autonomous_transaction;  
cek varchar2(5);  
begin  
commit;  
  cek := :new.val;  
dbms_output.put_line('Cek cek: ' || cek);  
update B set val = :new.val where id = :new.id;  
commit;  
end;  
/

Best Answer

Related Solutions

Trigger or check constraint insert values based upon existence of others

How to commit transaction on an after update event trigger

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