declare  
  ln_cnt integer;
begin
  for rc in (select * from user_tab_columns where data_type = 'VARCHAR2') loop
      execute immediate 'begin select count(1) into :cnt from '||rc.table_name||' where rtrim('||rc.column_name||') !='||rc.column_name||';end;'
        using out ln_cnt;
    if  0  != ln_cnt then
      dbms_output.put_line(rc.table_name||'.'||rc.column_name);       
      dbms_output.put('try to update...');
      
      begin
        execute immediate 'update '||rc.table_name||' set '||rc.column_name||'=rtrim('||rc.column_name||')';
        dbms_output.put_line('done');
      exception when others then
        dbms_output.put_line('error');
      end;
            
    end if;    
  end loop;
end;  

execute immediate 'begin select max(unn) into :res from opr; end;'; using Result; 

execute immediate 'begin select max(unn) into :res from opr; end;'; using out Result;