```SELECT DISTINCT a.num,a.company,stop_b.name,c.num,c.company
(为什么表头没有a.xx b.xx 这里查询的时候可以这样用啊?是num里面其中一条数据a的意思吗?)
FROM route a
JOIN route b ON a.company = b.company AND a.num = b.num
JOIN route c
JOIN route d ON c.company = d.company AND c.num = d.num
JOIN stops stop_a ON a.stop = stop_a.id
JOIN stops stop_b ON b.stop = stop_b.id
JOIN stops stop_c ON c.stop = stop_c.id
JOIN stops stop_d ON d.stop = stop_d.id
WHERE stop_a.name = 'Craiglockhart'
AND stop_d.name = 'Lochend'
AND stop_b.name = stop_c.name;
求解为什么要这样写?用户运营会简单的查询语句够不够用?
```