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

Or just create a sequence and maintain the pk field using the sequence to generate the primary key value with nextval function. And if perf is an issue, use cache on sequence.

But as others have stated, this is sub-optimal, if your primary key contains a numbered sequence then it's better to use int and auto-increment. I don't see a use case where pk has to auto-increment but be a varchar data type, it doesn't make sense.

Answer 2

you have to use an INT field
and translate it to whatever format you want at select time

Answer 3

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.