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

Question

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

Answer 1

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;
/