Codeigniter和SQL / Haversine公式 [英] Codeigniter and SQL/Haversine Formula

问题描述

我正在为项目使用Codeigniter，并且在数据库上有一些带有经度和纬度输入的位置。我正在尝试在一定距离（50公里）内获取积分，并尝试使用Haversine公式。但是，在我的控制器上查看并不会打印出结果。我需要知道的是，是否需要进行任何调整才能使模型功能正常工作。

I am using Codeigniter for a project and have some locations with latitude and longitude inputs on the database. I'm trying to get points within a certain distance (50km), and attempting it with the Haversine Formula. However, on my controller and view it doesn't print out the results. What I need to know is if there's any adjustments I need to make to get the model function working.

注意：数据库表具有列名称location_latitude和location_longitude。

Note: The DB table has the column names location_latitude and location_longitude.

//base function to compare distance with
$setlat = 13.5234412; 
$setlong = 144.8320897; 
//query with Haversin formula 
$awaka = "SELECT 'location_id',
    ( 3959 * acos( cos( radians(?) ) * cos( radians('location_latitude') ) * cos( radians('location_longitude') - radians(?) )
    + sin( radians(?) ) * sin( radians('location_latitude') ) ) ) AS 'distance'
    FROM 'locations' HAVING 'distance < 5'";
 $result = $this->db->query($awaka, array($setlat, $setlong, $setlat));  
 echo $result; 

推荐答案

似乎您被Haversine绊倒了式。您在第三个余弦 $ setlong 和 location_longitude 项>学期。我将它们切换到了这个位置：

It appears you got a little tripped up by the Haversine formula. You switched the $setlong and location_longitude terms in the third cosine term. I switched them around to get this:

$setlat = 13.5234412; 
$setlong = 144.8320897; 
$awaka = "SELECT 'location_id',
    ( 3959 * acos( cos( radians(?) ) * cos( radians('location_latitude') ) * cos( radians(?) - radians('location_longitude') )
    + sin( radians(?) ) * sin( radians('location_latitude') ) ) ) AS 'distance'
    FROM 'locations' HAVING 'distance < 5'";
$result = $this->db->query($awaka, array($setlat, $setlong, $setlat));  
echo $result;

看看此页面，该页面显示您必须编写Haversine公式才能找到两点之间的距离。

Have a look at this page, which shows you have to code up the Haversine formula to find the distance between two points.

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