数据表中的索引id如何重置？

向表中添加数据，索引值依次为1、2、3、4、5、6...
比如删除一些数据行后，id值变为1、3、4、6，这时我想把索引id重置为1、2、3、4，请问这该怎么整？

SQL code

新建表create table 新表(id int auto_increment primary key,col2 int,col3 int)

insert into  新表(col2,col3)
select  col2,col3
from 老表

rename table 老表 to  temp,新表 to 老表

SQL code

mysql> create table tt (id int auto_increment primary key,c int);
Query OK, 0 rows affected (0.08 sec)

mysql> insert into tt (c) values (10),(20),(30),(40),(50);
Query OK, 5 rows affected (0.05 sec)
Records: 5  Duplicates: 0  Warnings: 0

mysql> select * from tt;
+----+------+
| id | c    |
+----+------+
|  1 |   10 |
|  2 |   20 |
|  3 |   30 |
|  4 |   40 |
|  5 |   50 |
+----+------+
5 rows in set (0.00 sec)

mysql> delete from tt where id =3;
Query OK, 1 row affected (0.00 sec)

mysql> select * from tt;
+----+------+
| id | c    |
+----+------+
|  1 |   10 |
|  2 |   20 |
|  4 |   40 |
|  5 |   50 |
+----+------+
4 rows in set (0.00 sec)

mysql> update tt a ,(select b.id,count(*) as cid from tt b,tt c where b.id>=c.id
 group by b.id) d
    -> set a.id=d.cid
    -> where a.id=d.id;
Query OK, 2 rows affected (0.00 sec)
Rows matched: 4  Changed: 2  Warnings: 0

mysql> select * from tt;
+----+------+
| id | c    |
+----+------+
|  1 |   10 |
|  2 |   20 |
|  3 |   40 |
|  4 |   50 |
+----+------+
4 rows in set (0.00 sec)

mysql>