Given the following schema:
- Staff (sid, sname)
- Project (pid, pdesc, pfrom, pto)
- Asset (aid, acat, adesc)
- Workfor (sid, pid, wfrom, wto)
- Assignment (aid, sid, pid, afrom, ato)
Note: The bold attributes are the keys.
Find the names of the staffs who worked or are working for more than one project, in Tuple Relational Calculus.
I was thinking of using count() but it is not allowed in TRC (or according to my Prof). Any answers appreciated.