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# Self join Quiz

[Link](https://sqlzoo.net/wiki/Self_join_Quiz)

1. Select the code that would show it is possible to get from Craiglockhart to Haymarket

```sql
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?

```sql
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?

```sql
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'
```