I am trying to create a PL/SQL trigger that copies the current version of a row into a history table when the row is updated. This can be easily done like this:
CREATE OR REPLACE TRIGGER foo BEFORE UPDATE ON bar FOR EACH ROW
BEGIN
INSERT INTO bar_history VALUES bar.id = :old.id, bar.col1 = :old.col1 /* ...and so on */;
END;
However, I would like to avoid enumerating all the column names since the tables bar and bar_history are identical and I don't want to update the trigger every time I change the table. I have tried two approaches, none of which are working. Is there any other way to solve this?
Approach 1:
CREATE OR REPLACE TRIGGER foo BEFORE UPDATE ON bar FOR EACH ROW
BEGIN
INSERT INTO bar_history VALUES :old;
END;
Since you apparently can not use :old as a rowtype (see this question) I get the following error message:
PLS-00049: bad bind variable 'OLD'
Approach 2:
CREATE TRIGGER foo BEFORE UPDATE ON bar FOR EACH ROW
BEGIN
INSERT INTO bar_history
SELECT * FROM bar WHERE id = :old.id;
END;
This also gives me an error:
ORA-04091: BAR is mutating, trigger/function may not see it