Database using Relational Algebra

Consider the following schema: Supplier (sid, sname, address) Part (pid, pname, color) Cata- log (sid, pid, cost) The primary keys are underlined. The Catalog relation list the process charged for parts by supplies. Write each of the following queries by relational algebra 1. Find the sids of suppliers who supply every red or supply every green part 2. Find pairs of sids such that the supplier with the first sid charges more for some part than the supplier with the second sid. 3. Find the pids of parts supplied by at least two different suppliers 4. Find the pids of the most expensive parts supplied by suppliers named Ahmed 5. Find the pids of parts supplied by every supplier at less than 200S. (If any sup- plier does not supply the part or charges more than 200 $ for it, the part is not selected.)