The other day my developer told me that its impossible to migrate database info like passwords and usernames from one script to another one (a newly developed one).I would like to know if he was telling the truth. Thanks
I think you probably need to explain in more detail what you're trying to do? If your data is stored in a database then it should be accessible from any part of your website - whatever language it's written in. However - there might be factors such as encryption or hashing that make it harder to acheive.
It usually comes down to how the password is hashed. If you know the hashing mechanism for the passwords, it is usually not a problem. If you don't know how the password that is stored in the database is generated, then it's probably not possible. There will be no way to authenticate a user.