To change values of existing integer field (`table` is the table name, and "id" is the column name), you may use the following update SQL command:
update `table` set id=id+10000;
Let's say that you have an ecommerce website, and you want your order number to begin 10001. But, you already have a handful of orders already so you'll just update the existing values.
If you're updating your primary key values, MySQL will automatically adjust auto_increment value to begin after the largest number stored in the database.
To reset your auto increment value in MySQL database:
alter table `table` auto_increment = 1;
Notice, we are setting the auto_increment value to 1. By assigning 1, MySQL will automatically find the largest number and increment by 1. You may verify this by "SHOW CREATE TABLE" MySQL command.
% mysql mysql> show create table `table`
| table | CREATE TABLE `table` (
`id` int(3) unsigned NOT NULL AUTO_INCREMENT,
...
PRIMARY KEY (`id`),
) ENGINE=MyISAM AUTO_INCREMENT=6132 DEFAULT CHARSET=latin1
You may find other MySQL functions and operator useful. For example, if you wish to replace incorrectly added backslashes from a table column:
UPDATE table_name SET col = REPLACE(col, '\\', '')
References:
MySQL functions and operators