class information responsibilities

i have 'purchase order' class. contains information unparalleled squeeze order. i have dao category database methods.

where should accountability reside methods bucket transform squeeze order?

should purchaseorder category have '.update', 'insert', 'delete', '.load' methods dao category directly, should purchaseorder category ignorant dao methods have pocontroller category manages interactions?

the user wholly operative unparalleled purchaseorder during time.

thanks!