change auto_increment within same table using subquery mysql

Question

I am using mysql. I have a database table with auto_increment counter set. Now because of a requirement I need to leave starting 100 ids free and move all existing records s

Answer 1

In response to @Peter, it appears that you will have to update the AUTO_INCREMENT value after changing changing an existing one. The following example was done on MariaDB 10.0.12:

MariaDB [test]> show create table m;
+-------+--------------------------------------------------------+
| Table | Create Table                                           |
+-------+--------------------------------------------------------+
| m     | CREATE TABLE `m` (                                     |
|       |`id` int(10) unsigned NOT NULL AUTO_INCREMENT,          |
|       |`t` varchar(10) NOT NULL DEFAULT '',                    |  
|       |PRIMARY KEY (`id`)                                      |
|       |) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+-------+--------------------------------------------------------+
1 row in set (0.00 sec)

MariaDB [test]> insert into m (t) values ('a'),('b');
Query OK, 2 rows affected (0.03 sec)
Records: 2  Duplicates: 0  Warnings: 0

MariaDB [test]> select * from m;
+----+---+
| id | t |
+----+---+
|  1 | a |
|  2 | b |
+----+---+
2 rows in set (0.00 sec)

MariaDB [test]> update m set id=id+10;
Query OK, 2 rows affected (0.05 sec)
Rows matched: 2  Changed: 2  Warnings: 0

MariaDB [test]> select * from m;
+----+---+
| id | t |
+----+---+
| 11 | a |
| 12 | b |
+----+---+
2 rows in set (0.00 sec)

MariaDB [test]> show create table m;
+-------+--------------------------------------------------------+
| Table | Create Table                                           |
+-------+--------------------------------------------------------+
| m     | CREATE TABLE `m` (                                     |
|       |`id` int(10) unsigned NOT NULL AUTO_INCREMENT,          |
|       |`t` varchar(10) NOT NULL DEFAULT '',                    |  
|       |PRIMARY KEY (`id`)                                      |
|       |) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=latin1 |
+-------+--------------------------------------------------------+
1 row in set (0.00 sec)

MariaDB [test]> insert into m (t) values ('c');
Query OK, 1 row affected (0.04 sec)

MariaDB [test]> select * from m;
+----+---+
| id | t |
+----+---+
|  3 | c |
| 11 | a |
| 12 | b |
+----+---+
3 rows in set (0.00 sec)

MariaDB [test]>