how to manage fifo order for users and machines

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SQL-Server

Hello all,
here is issue:

i had two tables users and machines ,
i need to assign automatic users to each machine but in fifo order based on date some users are restricted to use particular machines.
example
there are 25 users
5 machines
i need to assign all user to 5 machines trick is user5 restricted for machine5 like....that


thanks®ards
Vamsi krishna j