MAX function for Strings


First of all, I’m having a Great experience using Airtable.
No doubt for me, it’s a Great solution.
Sure there’re rooms for improvement and plenty of functionalities to create.

One of them would be to have a MAX and MIN function for strings.

My use case is 2 linked tables, Master and Details.
I need to have a RollUp column in Master that refers to a MAX(value) of a string column in Detail.

Any other ways I can achieve that?

Keep the good work,