I agree: you are confused.
What kind of 'automatic number generation' are you talking about?
Should the numbers be unique?
Should they be ordered, or, maybe, sequential?
If you need to combine 'alphabets and current date' then you probably have to generate (possibly unique) identifiers, i.e.
strings not numbers.
Why don't you just use an available tool for generating unique id, like for instance
guidgen[
^]?