[英]select restaurant table entries within a certain distance from current location using php
i have a database table with a list of restaurants including their names, latitudes, and longitudes. 我有一个数据库表,其中包含餐厅的列表,包括餐厅的名称,纬度和经度。 i would like to select all the restaurants that are within a certain distance from my current location.
我想选择距离我当前位置一定距离内的所有餐厅。 the current location is determined in the php file (right now i'm just using a static lat & lng).
当前位置在php文件中确定(现在我只是使用静态lat&lng)。 i found code for calculating the distance:
我找到了计算距离的代码:
function findDist($lat, $lng){
$currLat = 33.777563;
$currLng = -84.389959;
$currLat = deg2rad ($currLat);
$sincurrLat = sin ($currLat);
$lat = deg2rad ($lat);
$currLng = deg2rad ($currLng);
$lng = deg2rad ($lng);
return round((7926 - 26 * $sincurrLat) * asin (min (1, 0.707106781186548 * sqrt ((1 - (sin ($lat) * $sincurrLat) - cos ($currLat) * cos ($lat) * cos ($lng - $currLng))))),4);
}
but how do i incorporate that into my select query? 但是如何将其合并到我的选择查询中? i tried this:
我试过这个:
$query = "SELECT *
FROM
eateries E
WHERE
EXISTS
(
SELECT *
FROM
eateries_hours EH, eateries_type ET
WHERE
EH.eateries_id = E.id AND ET.eateries_id = E.id
AND findDist(E.lat, E.lng) <= .5
)";
but of course that doesn't work because it's not recognizing the function. 但这当然不起作用,因为它无法识别该功能。 can i do a separate query just for lats and lngs at first, calculate the distances, and then join that with the above query somehow?
我可以先对纬度和经度进行单独的查询,计算距离,然后以某种方式将其与上述查询结合吗? any ideas?
有任何想法吗?
thanks. 谢谢。
Take a look at a question that I previously answered. 看一下我之前回答的问题 。 You can create a stored function in MySQL (or other databases) that does this provided that you have the latitudes and longitudes.
您可以在MySQL(或其他数据库)中创建一个存储函数,前提是您具有经度和纬度。
DELIMITER $$
DROP FUNCTION IF EXISTS `FindDist` $$
CREATE FUNCTION `FindDist` (lt1 DOUBLE,lg1 DOUBLE,lt2 DOUBLE,lg2 DOUBLE) RETURNS DOUBLE
DETERMINISTIC
BEGIN
DECLARE dist,eradius DOUBLE;
SET eradius=3963.1;
SET dist=Acos(Cos(lt1) * Cos(lg1) * Cos(lt2) * Cos(lg2) + Cos(lt1) * Sin(lg1) * Cos(lt2) * Sin(lg2) + Sin(lt1) * Sin(lt2)) * eradius;
RETURN dist;
END $$
DELIMITER ;
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