以前写的，笨办法，不知道大家有什么好的办法没有？

表结构：
/*DDL Information For - t_girl.yld1*/
-------------------------------------

Table   Create Table                                            
------  ---------------------------------------------------------
yld1    CREATE TABLE `yld1` (                                   
          `id` int(11) default NULL,                            
          `uid` int(11) default NULL                            
        ) ENGINE=MyISAM DEFAULT CHARSET=utf8 ROW_FORMAT=DYNAMIC


初始数据：

query result(4 records)

id uid
(NULL) 6
(NULL) 5
2 (NULL)
1 (NULL)

执行过程：
create table yld2 select * from yld1

delete from yld1 where id is null;
delete from yld2 where id is not null;
alter table yld1 add autoid int not null AUTO_INCREMENT primary key;
alter table yld2 add autoid int not null AUTO_INCREMENT primary key;

update yld1 as a,yld2 as b set a.uid = b.uid where a.autoid = b.autoid;

alter table yld1 drop autoid;

drop table yld2;


 最终结果：

query result(2 records)

id uid
2 6
1 5