Fine Grained Auditing for Oracle XE

Oracle XE does not have FGA (Fine Grained Auditing).
So I had to implement a package and a trigger in order to keep a fine grained record of what data and what column and on what table was the data added,deleted or inserted.
I received quite a bit of help from the Oracle Forum.
I have created a table called "audit_logs" to store the records of inserts,deletes and updates.

Below is the SQL structure for the "audit_logs" table.

CREATE TABLE  "AUDIT_LOGS" 
   (  "TABLENAME" VARCHAR2(4000), 
  "COLUMNNAME" VARCHAR2(4000), 
  "USERNAME" VARCHAR2(4000), 
  "OLDVAL" VARCHAR2(4000), 
  "NEWVAL" VARCHAR2(4000), 
  "AUDITDATE" TIMESTAMP (6)
   )
/

Below is the code for the "auditpkg" package.

create or replace package auditpkg AS -- package spec
  procedure auditproc( p_tablename varchar2, p_columnname varchar2,
    p_oldval varchar2, p_newval varchar2 );
  procedure auditproc( p_tablename varchar2, p_columnname varchar2,
    p_oldval number, p_newval number );
  procedure auditproc( p_tablename varchar2, p_columnname varchar2,
    p_oldval date, p_newval date );
end auditpkg;

/

SHOW ERRORS

create or replace package body auditpkg AS -- package body   
  procedure auditproc
( p_tablename varchar2, p_columnname varchar2, p_oldval varchar2, p_newval varchar2 ) 
  IS
  BEGIN
      if (p_oldval is null and p_newval is not null)
      or (p_oldval is not null and p_newval is null)
      or (p_oldval != p_newval)
      then
insert into audit_logs( tablename, columnname, username, oldval, newval, auditdate )
  values (p_tablename, p_columnname, USER, p_oldval, p_newval, SYSDATE );
      end if;
  END auditproc;

  procedure auditproc
( p_tablename varchar2, p_columnname varchar2, p_oldval number, p_newval number ) 
  IS
  BEGIN
      if (p_oldval is null and p_newval is not null)
      or (p_oldval is not null and p_newval is null)
      or (p_oldval != p_newval)
      then
insert into audit_logs( tablename, columnname, username, oldval, newval, auditdate )
  values (p_tablename, p_columnname, USER, p_oldval, p_newval, SYSDATE );
      end if;
  END auditproc;

  procedure auditproc
( p_tablename varchar2, p_columnname varchar2, p_oldval date, p_newval date ) 
  IS
  BEGIN
      if (p_oldval is null and p_newval is not null)
      or (p_oldval is not null and p_newval is null)
      or (p_oldval != p_newval)
      then
insert into audit_logs( tablename, columnname, username, oldval, newval, auditdate )
  values (p_tablename, p_columnname, USER, p_oldval, p_newval, SYSDATE );
      end if;
  END auditproc;

END auditpkg;   

/
SHOW ERRORS

Below is the code for the "audit_test_audit_trig" trigger
There must be one trigger for each table, each with its own unique trigger name of course.
In the case below, the trigger is for a table called "audit_test"

create or replace trigger audit_test_audit_trig
after insert or update or delete on audit_test
for each row
begin
  auditpkg.auditproc( 'AUDIT_TEST', 'COL1', :old.col1, :new.col1 );
  auditpkg.auditproc( 'AUDIT_TEST', 'COL2', :old.col2, :new.col2 );
  auditpkg.auditproc( 'AUDIT_TEST', 'COL3', :old.col3, :new.col3 );
end;