Reset the Index of a MySQL table

Sometimes, I will be playing about with a MySQL database, often at the start of an application. I'll fire a load of dummy data in and test. When I've finally done with this phase I'm ready to start from the beginning. I might have an ID field which I'd like to auto increment but this time starting from 0. To reset this field, first empty all the records in the table, then you can apply a line like this:
ALTER TABLE `mytable` AUTO_INCREMENT=0