Find N Nearest LineString From A Point Using MySQL Spatial Extensions

Question

I\'m using MySQL Spatial Extensions to store data about roads and hotels. I store the hotel data as a Point while I store the road data as LineString. The tables look like this<

Answer 1

This was a very useful answer for me, but I'm using MySQL 5.7.18, which has more advanced or just different geo query functions. The distance function posted isn't needed anymore- use ST_Distance_Sphere. So here's an update of the same code to make DistanceFromLine compliant with modern (5.7.6+) MySQL...

DROP function IF EXISTS `DistanceFromLine`;
delimiter //
    CREATE FUNCTION `DistanceFromLine`(
    route LINESTRING, point1 POINT
    ) RETURNS INT DETERMINISTIC
        BEGIN
        DECLARE a INT Default 0 ;
        DECLARE minDistance INT Default 0;
        DECLARE currentDistance INT Default 0;
        DECLARE currentpoint point ;
        DECLARE size INT Default 0 ;
        SET size =  ST_NumPoints(route);
              simple_loop: LOOP
       SET a = a+1;
       SET currentpoint = ST_PointN(route,a);
       SET currentDistance = ST_Distance_Sphere(point1,currentpoint);

       IF a = 1 THEN
        SET minDistance = currentDistance;
           END IF;

       IF currentDistance < minDistance THEN
        SET minDistance = currentDistance;
       END IF;
       IF a=size THEN
                 LEAVE simple_loop;
       END IF;
          END LOOP simple_loop;
     RETURN (minDistance);
 END//