In Alabama, it is illegal for an adult (someone 18 or older) to have sex with a minor (someone younger than 16), even if the sex is consensual. Those who break the law have committed statutory rape.

Is it OK for a 16 to date a 30-year-old?

This means that its against the law for someone to have sex with someone under the age of 16. It wouldnt be illegal for someone whos 16 to have a relationship with someone who is 30 - unless that person is their teacher or in a position of authority.

Can a 28 year old date a 17 year old in Alabama?

Yes it is illegal.