text: SELECT P.pid
  FROM Parts P, Catalog C
  WHERE P.pid = C.pid AND C.cost < 10;
  
  SELECT P.pname
  FROM Parts P, Catalog C
  WHERE P.pid = C.pid AND C.cost < 10;
  
  SELECT S.address
  FROM Suppliers S, Parts P, Catalog C
  WHERE S.sid = C.sid AND P.pid = C.pid AND P.pname = 'Fire Hydrant Cap';
  
  SELECT S.sname
  FROM Suppliers S, Parts P, Catalog C
  WHERE S.sid = C.sid AND P.pid = C.pid AND P.color = 'Green';
  
  SELECT S.sname, P.pname
  FROM Suppliers S, Parts P, Catalog C
  WHERE S.sid = C.sid AND P.pid = C.pid;
  