使用 POINT 的 Mysql 空间距离 - 不工作

My goal is to use mysql POINT(lat,long) to find nearby entities in the database. I'm trying to do something like in the bottom of this tutorial http://www.scribd.com/doc/2569355/Geo-Distance-Search-with-MySQL . Here is what I have got:

表:

CREATE TABLE mark (
id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
name VARCHAR(20) DEFAULT NULL,
loc POINT NOT NULL,
SPATIAL KEY loc (loc)
) ENGINE=MyISAM;

插入一些测试数据:

 INSERT INTO mark (loc,name) VALUES (POINT(59.388433,10.415039), 'Somewhere 1');
 INSERT INTO mark (loc,name) VALUES (POINT(63.41972,10.39856), 'Somewhere 2');

声明距离函数:

 DELIMITER $$
 CREATE FUNCTION `distance`
 (a POINT, b POINT)
 RETURNS double DETERMINISTIC
 BEGIN
 RETURN
 round(glength(linestringfromwkb(linestring(asbinary(a),
 asbinary(b)))));
 END $$
 DELIMITER;     

尝试使用函数搜索ex.:

 SELECT name, distance(mark.loc, GeomFromText( ' POINT(31.5 42.2) ' )) AS cdist
 FROM mark
 ORDER BY
 cdist limit 10;

 SELECT DISTINCT
 dest.name,
 distance(orig.loc, dest.loc) as sdistance
 FROM
 mark orig,
 mark dest
 having sdistance < 10
 ORDER BY
 sdistance limit 10;

 SELECT  glength(LineStringFromWKB(LineString(GeomFromText(astext(PointFromWKB(POINT(63.424818,10.402457)))),GeomFromText(astext(PointFromWKB(POINT(663.422238,10.398996)))))))*100 
 AS distance;