Select items within range using MySQL spatial extensions?

问题

I am completely new to MySQL spatial extensions, so please excuse my ignorance on the topic.

The scenario:

1) I collect a user's location via latitude and longitude. I store that location in a MySQL table.

2) I then display any other users within a range of that user. The range would be small - let's say 1000 ft.

Question: What is the best practice for storing the location points? What is the best practice for querying and selecting the points nearest that user?

回答1:

• Use the POINT Spatial datatype to store the coordinates.

  The structure is like this:

   CREATE TABLE gps name varchar(0), `location` point NOT NULL;
  

  Please note the type of column 'location'.

• After that, you have to define a SPATIAL index for the 'location' column.

  CREATE SPATIAL INDEX sp_index ON gps(`location`);
  

• Inserting data (latitude and longitude)

  INSERT INTO gps (name, location) VALUES ( 'India' , GeomFromText( ' POINT(31.5 42.2) ' ) ) 
  

  The function GeomFromText takes a string and returns a Geometry Object. Here 31.5 and 42.2 are latitude and longitude respectively. Note that there is NO comma between them. They are delimited by a space.

• Reading data

  SELECT name, AsText(location) FROM gps;
  

  The AsText function converts the internal representation of a geometry to a string format.

  Note: You have to use MySQL 5.0 or above the spatial extension support. Also use 'MyIsam' db engine for faster queries.

回答2:

Unfortunately there is no such function in MySQL as select points in radius. But you can easily use this cosine law formula: d = acos( sin(φ1)*sin(φ2) + cos(φ1)*cos(φ2)*cos(Δλ) )*R to get distance between 2 points. You can find details here: http://www.movable-type.co.uk/scripts/latlong-db.html SQL query will look like this:

SELECT acos(sin(radians(Y(point1)))*sin(radians(Y(point2))) + cos(radians(Y(point1)))*cos(radians(Y(point2)))*cos(radians(X(point2))-radians(X(point1)))) * 6371 AS `distance`
FROM locations

来源：https://stackoverflow.com/questions/15034024/select-items-within-range-using-mysql-spatial-extensions