Second Auto-increment

I would like to auto-increment within an auto-incremented value. For example, if I have a rental agreement(auto-incremented) and that rental agreement becomes month-to-month. I was thinking that I would want to track the receipts as such: Contract # | Type | Second Auto # | Duration |payment t

Securing a Website driven with MySQL/PHP/Apache

I am in the process of developing a MySql database driven website but I need to know that it is secure. Should the User Authentication Password stored in the database be encryted? And if so, how? Any other security tips are welcome..! Thanks. - Do you Yahoo!?