How to select random subset of cases in SPSS based on student number?

How to select random subset of cases in SPSS based on student number?

I am setting some student assignments where most students will be using
SPSS. In order to encourage students to do their own work, I want students
to have a partially unique dataset. Thus, I'd like to get each to the open
the master data file, and then get the student to run a couple of lines of
syntax that produces a unique data file. In pseudo code, I'd like to do
something like the following where 12345551234 is a student number:
set random number generator = 12345551234
select 90% random subset ofcases and drop the rest.
What is simple SPSS syntax dropping a subset of cases from the data file?