出至：http://ariejan.net/2007/11/30/mysql-reset-the-auto-increment-value-of-a-table/
MySQL: (Re)set the auto-increment value of a table
Written by Ariejan de Vroom on 30 November 2007.
via Ad Packs
Sometimes it’s necessary to set the starting point of a MySQL auto-increment value.
Normally, MySQL starts auto-incrementing at 1. But let’s say you want to start at 10.000, because you want at least a five figure number. You can use the following query to set the MySQL auto-index:
ALTER TABLE some_table AUTO_INCREMENT=10000
If you want to delete all records from your table and restart auto-index at 1, you might be tempted to run a DELETE query, followed by the above example, setting the auto increment value to 1. There is a shortcut, however:
TRUNCATE TABLE some_table
This will basically reset the table, deleting all data and resetting the auto increment index. Do not that the truncate command is a hard-reset option. For instance, any triggers “ON DELETE” will not be fired when using truncate.
Jerry-Yang's Log 