Given the relations

employee (name, salary, deptno), and
department (deptno, deptname, address)

Which of the following queries cannot be expressed using the basic relational algebra operations $$\left(\sigma, \pi,\times ,\Join, \cup, \cap,-\right)$$?

B⁺-trees are preferred to binary trees in databases because

Given the following relation instance
$$\eqalign{ & X\,\,\,\,\,Y\,\,\,\,\,Z \cr & \,\,1\,\,\,\,\,\,4\,\,\,\,\,\,2 \cr & \,\,1\,\,\,\,\,\,5\,\,\,\,\,\,3 \cr & \,\,1\,\,\,\,\,\,6\,\,\,\,\,\,3 \cr & \,\,3\,\,\,\,\,\,2\,\,\,\,\,\,2 \cr} $$

Which of the following functional dependencies are satisfied by the instance?

The following arrangement of master-slave flip-flop

Has the initial state of $$P, Q$$ as $$0, 1$$ (respectively). After three clock cycles the output states $$P, Q$$ is (respectively).