Find the nearest point from a given point in MySQL - mysql

Question

I have a set of points from which I created a multipoint.
SET #multi_point = ST_GeomFromText('MULTIPOINT(-118.2845938 34.0252385, -118.2867610 34.0221188, -118.2905912 34.0227248, -118.284119 34.021846, -118.2864676 34.0186438, -118.2886342 34.0203211, -118.2907290 34.0193680, -118.2831326 34.0192874, -118.2828242 34.0205473)');
I also have a single other point
SET #home = ST_GeomFromText('POINT(-118.2819136 34.0261177)')
From #home I want to find the nearest 3 points. that are a part of the multi-point #multi_point. I thought of first determining the distance from this point #home to every point in the multipoint using ST_DISTANCE. But I get the following:
SELECT ST_DISTANCE(#home, #multi_point)
+----------------------------------+
| ST_DISTANCE(#home, #multi_point) |
+----------------------------------+
| 0.0028207205958764945 |
+----------------------------------+
It looks like I only get the shortest distance of the point to the multipoint. Questions:
Is there a way to get the shortest distance to every point, and determine the points themselves?
Is there a better way to determine the nearest neighbors from one point #home to the rest in #multi_point?
EDIT I tried Paul Spiegel's of storing these points in a table. But when I store a Point type, it is stored as a garbage value:
+-----------------+---------------------------+
| Name | Coordinates |
+-----------------+---------------------------+
| P1 | [2]pxA# |
| p2 | +1Z]:PA# |
| p3 | a]KA# |
| p4 | X ]qgpA# |
| p5 | EW3|U]A# |
| p6 | M]bKzA# |
| p7 | Ku/]2ƇA# |
| p9 | =];A# |
| p8 | u`x]A# |
+-----------------+---------------------------+
Also, When I query it, the distances are null.
SELECT P.Name, ST_DISTANCE(#home, P.Coordinates) AS dist
FROM Placemark P ORDER BY dist LIMIT 3;
+--------------+------+
| Name | dist |
+--------------+------+
| p1 | NULL |
| p2 | NULL |
| p3 | NULL |
+--------------+------+
How do I fix this?

Answer 1

Here is an example using a temporary table:
drop temporary table if exists Placemark;
create temporary table Placemark(
Name varchar(50),
Coordinates point
);
insert into Placemark(Name, Coordinates) values
('p1', POINT(-118.2845938, 34.0252385)),
('p2', POINT(-118.2867610, 34.0221188)),
('p3', POINT(-118.2905912, 34.0227248)),
('p4', POINT(-118.284119 , 34.021846 )),
('p5', POINT(-118.2864676, 34.0186438)),
('p6', POINT(-118.2886342, 34.0203211)),
('p7', POINT(-118.2907290, 34.0193680)),
('p8', POINT(-118.2831326, 34.0192874)),
('p9', POINT(-118.2828242, 34.0205473));
SET #home = ST_GeomFromText('POINT(-118.2819136 34.0261177)');
SELECT
P.Name,
ST_AsText(P.Coordinates) as Coordinates,
ST_DISTANCE(#home, P.Coordinates) AS dist
FROM Placemark P
ORDER BY dist
LIMIT 3
The result:
Name | Coordinates | dist
p1 | POINT(-118.2845938 34.0252385) | 0.00282072059587649
p4 | POINT(-118.284119 34.021846) | 0.00480741199088132
p9 | POINT(-118.2828242 34.0205473) | 0.00564433773972052
Demo: http://rextester.com/GMPK57301
To define a POINT use either POINT(-118.2845938, 34.0252385) or ST_GeomFromText('POINT(-118.2845938 34.0252385)'). To see the value in a readable form use ST_AsText().