create or replace trigger del_ins_upd
  BEFORE INSERT OR DELETE OR UPDATE ON customer
  for each row
  DECLARE
  v_sysdate varchar2(25);
  v_row_count := sql%rowcount;
begin
  

  select to_char(sysdate,'DD-MON-YYYY HH:MM:SS') into v_sysdate from dual;
  
    IF INSERTING THEN
      
      insert into results(output)
                      values (' CUSTOMER table was modified '|| v_row_count ||
                      ' rows have been inserted at ' || v_sysdate); 
    ELSIF UPDATING THEN
      insert into results(output)
                      values (' CUSTOMER table was modified '|| 
                      ' rows have been updated at ' || v_sysdate);
    ELSIF DELETING THEN
      insert into results(output)
                      values (' CUSTOMER table was modified '|| 
                      ' rows have been deleted at ' || v_sysdate);
    ELSE 
      dbms_output.put_line('UNKNOWN');
    END IF;

end;
/

orcl>
orcl> var retval varchar2(50)
orcl> update emp set sal=sal*1 where deptno=10
  2  returning count(*)||' rows updated at '||max(sysdate) into :retval;

3 rows updated.

orcl> print retval

RETVAL
------------------------------------------------------------------------------

3 rows updated at 21-12-11 16:59:25

orcl>