当你从数据库mysql中删除一条记录时

i'm new to the whole database scenario and just learning. I have a database mysql and i am using phpmyadmin to edit fields etc. I created a auto_incremenet 'id' field that is set as a primary. If i add 5 fields, the id will be '1,2,3,4,5'. If i delete all those fields and add another 5 fields, why does the ID go to '6,7,8,9,10'? (instead of going back to 0, since technically the other fields do not exist anymore so its unique right?). Is there a way to make the id be sequentially numeric? 1,2,3,4,5 ? i'm new to the whole database scenario and just