Java system generated username and password in a distributed environment

I want to develop a distributed student registration system which will allow several administrators to enter student information in textfields and submit this information to the database, to create their records concurrently. The system should then automatically create a username in the form(200400001 as the first username) and a unique password made up of digits and characters. This username and password should also be submitted to the database in the same table where the student information is stored. The problem is how can I synchronize the username creation to allow several administrators to create student records at the same time.I will appreciate any suggestion of code or idea. Note: The system I am developing is client/ server and I am using sockets for communication of the client process and the server process.