Question

I’m trying to retrieve listings that are near a user’s current lat/long position.

Have tried MySQL’s geospatial POINT to no avail, so returning to using DECIMAL lat/lon values for each record.

The below function is meant to get the listings within 10km (based on this formula) I realise the SELECT isn’t quite right, but I’m not sure how to define the ((ACOS … 1.1515) as distance and then also select the other columns.

// functions.php
function getDeals($type_of_deal) {
    $current_lat = -37.905;
    $current_lon = 175.505
    $result = mysql_query("
    SELECT i, company, 
        TIME_FORMAT(valid_time_start, '%l:%i %p'), 
        TIME_FORMAT(valid_time_end, '%l:%i %p'), 
        DATE_FORMAT(valid_expiry, '%D %b %y'),
        ((ACOS(SIN("$current_lat" * PI() / 180) * SIN(`company_lat` * PI() / 180) + 
        COS("$current_lat" * PI() / 180) * COS(`company_lat` * PI() / 180) * 
        COS(("$current_lon" – `company_lon`) * PI() / 180)) * 180 / PI()) * 60 * 1.1515)
    AS distance
    FROM listings
    WHERE deal_type = '" .$type_of_deal. "'
    HAVING distance<=’10′ 
    ORDER BY `distance` ASC
    ");
return $result;

// location.php
$type_of_deal = food;
$result = getDeals($type_of_deal);
    if (mysql_num_rows($result)) {
        while($row = mysql_fetch_array($result)) {
            echo $row["deal_title"];
            }
     }

Answer 1

You can try looking into MySQL great circle distance. And you can also take a look @ Google maps SQL api. It shows how to find a location near another location.

Now looking specifically at your code you have a couple of errors.

1. No semicolon after statements:

   $current_lon = 175.505
   $result = mysql_query(“

2. No concatenation of strings (you use double quotes for your strings but also inside them).

3. No } after your function ends.

Here’s a quick cleanup of your code:

function getDeals($type_of_deal) {
    $current_lat = -37.905;
    $current_lon = 175.505
    $result = mysql_query('SELECT i, company, 
        TIME_FORMAT(valid_time_start, "%l:%i %p"), 
        TIME_FORMAT(valid_time_end, "%l:%i %p"), 
        DATE_FORMAT(valid_expiry, "%D %b %y"),
        ((ACOS(SIN('.$current_lat.' * PI() / 180) * SIN(`company_lat` * PI() / 180) + 
        COS('.$current_lat.' * PI() / 180) * COS(`company_lat` * PI() / 180) * 
        COS(('.$current_lon.' – `company_lon`) * PI() / 180)) * 180 / PI()) * 60 * 1.1515)
    AS distance
    FROM listings
    WHERE deal_type = "'.$type_of_deal.'"
    HAVING distance<=10 
    ORDER BY `distance` ASC');
    return $result;
}