MySQL - how to use VARCHAR as AUTO INCREMENT Primary Key

Question

I am using a VARCHAR as my primary key. I want to auto increment it (base 62, lower/upper case, numbers), However, the below code fails (for obvious reasons):

Answer 1

example of a solution to your problem:

create a file with a unique number and then increment with a function.

the filename can be the prefix and the file binary content represent a number.

when you need a new id to the reg invoque the function

Example

    String generateID(string A_PREFIX){
        int id_value = parsetoInt(readFile(A_PREFIX).getLine())
        int return_id_value = id_value++
        return return_id_value
    }

where "A_PREFIX-" is the file name wich you use to generate the id for the field.