Shortest Distance in a Line

这题因为是找同一列中元素的差值，现阶段会的方法就是再搞一张这个表出来两个之间再对比了

SELECT min(abs(p.x - another.x)) AS shortest
FROM point AS p 
JOIN (
    SELECT * FROM point
) another 
WHERE p.x <> another.x

答案也是这个思路，不过写法肯定更好

SELECT min(abs(p1.x - p2.x)) AS shortest
FROM point p1
JOIN point p2
ON p1.x <> p2.x