I have 3 tables that are related to each other, namely: student/ course,
student and student/department.

In the 3 tables I need to select the value for a department, using a drop
down box.
I also have a department table (deptid, deptname).

Is it okay to duplicate the department table so there will be a copy for
each child table that uses it and still maintain referential integrity?  It
would create a bit of an overhead having 3 copies of the same table, in case
someone updated the table and forgot to duplicate it.

(If I am not clear, I can explain using examples.)  What do you do in this
situation?

Thanks for your help!

Joy