613. Shortest Distance in a Line--ABS() and MIN()

Question

Table point holds the x coordinate of some points on x-axis in a plane, which are all integers.

Write a query to find the shortest distance between two points in these points.

| x   ||-----|| -1  || 0   || 2   |

The shortest distance is '1' obviously, which is from point '-1' to '0'. So the output is as below:

| shortest||---------|| 1       |

Note: Every point is unique, which means there is no duplicates in table point.

Follow-up: What if all these points have an id and are arranged from the left most to the right most of x axis?

SELECT    MIN(ABS(p1.x - p2.x)) AS shortestFROM    point p1        JOIN    point p2 ON p1.x != p2.x;