Should there be use cases = functional requirements?


Given UML, i'm having some confusions whith knowing if there should be the same amount of use cases as there are functional requirements. so lets say :

  ()_______________________________________Update Info.
  ||__________________ Create User

since there are 2 use cases, should i create 2 Funciontal Requirements ?

I would say not. That would only hold if there were a one-to-one relationship between requirements and Use Case, and that is not the case.

A requirement might result in multiple Use Cases. For example, a requirement to "have password protection" might result in one Use Case for what happens when a correct password is entered, and another Use Case for when the wrong password is entered.

On the other hand, a requirement might result in zero Use Cases. For example, a requirement to do a calculation within 1 second would not need a Use Case.