CREATE OR REPLACE TRIGGER TRG_DDL_CHANGES
AFTER alter    OR      drop
ON DATABASE
DECLARE
   PRAGMA AUTONOMOUS_TRANSACTION;
   v_username    VARCHAR2(30);
   v_osuser      VARCHAR2(1000);
   v_sql_text    ORA_NAME_LIST_T;
   v_stmt        VARCHAR2(4000);
   v_n           NUMBER;
   e_not_allowed EXCEPTION;
BEGIN
   v_osuser := SYS_CONTEXT('USERENV', 'OS_USER');
   IF v_osuser IS NOT NULL
   THEN -- The action is not a system initiated process.
      v_username := SYS_CONTEXT('USERENV', 'SESSION_USER');
      IF v_username IN ('WASIM','SCOTT','XXX' )
      THEN -- The Above Users Needs To Audited
         v_n := ORA_SQL_TXT(v_sql_text);
         FOR i IN 1..v_n LOOP
            v_stmt := v_stmt || v_sql_text(i);
         END LOOP;
            RAISE e_not_allowed;
         END IF;
      END IF;
EXCEPTION
   WHEN e_not_allowed
   THEN
      RAISE_APPLICATION_ERROR(-20101, 'Illegal Operation, DDL Not Allowed.  Please Contact the DBA.');
END;
/