Oracle获取表的字段作为变量

需要判断表中所有字段的数据是否符合要求，为了方便处理，需要或许字段作为变量

declare

  n number;

  sv_sql varchar2(1000);

begin

  for idx in (select t.COLUMN_NAME

                from user_tab_columns t

               where Table_Name = 'C_CIRCUIT'

               order by column_name) loop

    sv_sql := 'select count(1)from C_CIRCUIT where length(' || idx.column_name ||

              ') <>lengthb(' ||idx.column_name || ')';

    execute immediate sv_sql

      into n;

    if n <> 0 then

      insert into lm values (idx.column_name);

    end if;

  end loop;

  commit;

end;