automatically genterated alpha-numeric number

I would like to know if it is possible to have excel to automatically generated a number for like a invioce or to make an employee number or a customer number I have attached two forms to explain or for example. Thanks

One possible suggestion to consider:

Create the unique customer / invoice number by combining the phone number with the zip/postal code. This ought to prevent any duplicate numbers.

In general, a automated sequential number usually works well.
In some of my application where I need to serialize, I use this approach (does require a bit of VBA):

• Numeric cell that gets incremented (VBA)
• One cell that holds the function: YEAR(TODAY())
• VBA to join the two and write the value to a cell

The serial number ends up: 2009001, 2009002, etc.