求各位数据库的高手帮忙注解一下，我是新手才开始学习的！非常感谢！！！

declare
    sqltext varchar2(8000);
begin
/* sqltext := 'drop table dcl_temp45';
    execute immediate sqltext;*/
    sqltext := 'create table dcl_temp45 as select acct_id as ' || 'acct_id';
    for r_acct_month in (select distinct acct_month from dcl_temp44) loop
      sqltext := sqltext || ' , sum(case acct_month when ''' || r_acct_month.acct_month|| ''' then charge else 0 end) as  A' || r_acct_month.acct_month|| '';
    end loop;
    sqltext := sqltext || ' from dcl_temp44 group by acct_id order by acct_id';
   -----dbms_output.put_line(sqltext);
    execute immediate sqltext;
end;
/