2. Consider the following relations containing airline flight information: Flights(flno: integer, from: string, to: string, distance: integer, departs; time, arrives: time) Aircraft(aid: integer, aname: string, cruisingrange: integer) Certified(eid: integer, aid: integer) Employees(eid: integer,ename: string, salary: integer) Note that the Employees relation describes pilots and other kinds of employees as well; every pilot is certified for some aircraft (otherwise, he or she would not qualify as a pilot), and only pilots are certified to fly. Write the following queries in relational algebra, tuple relational calculus, domain relational calculus and SQL. Note that some of these queries may not be expressible in relational algebra (and, therefore, also not expressible in tuple and domain relational calculus)! For such queries, informally explain why they cannot be expressed. [17=7] (a) Find the eids of pilots certified for some Boeing aircraft. (b) Find the names of pilots certified for some Boeing aircraft. (c) Find the aids of all aircraft that can be used on non-stop flights from Bonn to Madras. (d) Identify the flights that can be piloted by every pilot whose salary is more than $100,000. (e) Find the names of pilots who can operate planes with a range greater than 3,000 miles but are not certified on any Boeing aircraft. (f) Find the eids of employees who make the highest salary. (g) Find the eids of employees who make the second highest salary