text: 1. Select the code that would show it is possible to get from Craiglockhart to Haymarket
  
  SELECT DISTINCT a.name, b.name
    FROM stops a JOIN route z ON a.id=z.stop
    JOIN route y ON y.num = z.num
    JOIN stops b ON y.stop=b.id
   WHERE a.name='Craiglockhart' AND b.name ='Haymarket'
  
   2. Select the code that shows the stops that are on route.num '2A' which can be reached with one bus from Haymarket?
  
  SELECT S2.id, S2.name, R2.company, R2.num
    FROM stops S1, stops S2, route R1, route R2
   WHERE S1.name='Haymarket' AND S1.id=R1.stop
     AND R1.company=R2.company AND R1.num=R2.num
     AND R2.stop=S2.id AND R2.num='2A'
  
  3. Select the code that shows the services available from Tollcross?
  
  SELECT a.company, a.num, stopa.name, stopb.name
    FROM route a JOIN route b ON (a.company=b.company AND a.num=b.num)
    JOIN stops stopa ON (a.stop=stopa.id)
    JOIN stops stopb ON (b.stop=stopb.id)
   WHERE stopa.name='Tollcross'