Triggers and user activity.

Question

hi, is it possible to create a trigger that will fire if a row or record is read during a query?
What I've been told is that triggers can only fire on,
Update,delete, and insert
Can anyone out there give me an asnwer to this. thanks.

Answer 1

I have thought of a way to do this in 8i (although I wouldn't recommend it). My example uses the EMP table from the SCOTT schema.
Create a table to hold audit info:
create table emp_audit_trail
  ( empno      number
  , username   varchar2(30)
  , audit_date date ); Create a function to save audit info, note the PRAGMA statement:
create function audit_emp
  ( p_empno     number )
return varchar2
is
  pragma autonomous_transaction;
begin
  insert into emp_audit_trail
    ( empno
    , username
    , audit_date )
  values
    ( p_empno
    , USER
    , SYSDATE );
  commit;
  return 'Y';
end; The PRAGMA ensures that the COMMIT is performed in a seperate transaction to the SELECT statement.
Now create a view over the EMP table:
create emp_v
as
select *
from   emp
where  audit_emp(emp_no) = 'Y';If you revoke public access to the EMP table, and ensure that everyone uses EMP_V, all SELECTs will be recorded in the Audit Trail table.