Emp (Eid, name, age)
Project(Pid, Pname, budget)
Works(Eid, Pid)
Select Eid from Emp E where age>30 not exists (Select Pid from Project P where Pname="database" and not exists (select Pid from Works W where W.Eid=E.Eid and W.Pid=E.Pid));
Above query retrieves employees whose
a) age more than 30 and works for every project with project name database.
b) age more than 30 and works for some project with project name database.
c) age more than 30 and not works for every project with project name database.
d) age more than 30 and not works for any project with project name database.
here Eid and Pid in every table is primary key.
answer given is option a, but i have doubt because am getting option b. someone please clarify my doubt with example.