显示用户在PHP中当前位置的10公里半径范围内的用户

Question

我有一个要求，我将从Android应用程序获得纬度和经度。根据收到的纬度和经度，我想从数据库中获取其他用户的信息。

用户应在半径5或10公里范围内，具有给定的纬度和经度。任何帮助表示赞赏。

Answer 1

如果您的数据库是MySQL，并且您的users表被命名为users，并且您想要找到半径10公里内的所有用户，那么使用CodeIgniter：

// You would supply real latitude and longitude values here.
// I used a location in the southwestern United States.
$lat      = '34.770498';
$lng      = '-116.015625';
$distance = 10; // Kilometers

$this->load->database();

$query = $this->db->query(
    '
    SELECT 
        *,
        6371 * 2 * ASIN(SQRT(POWER(SIN(RADIANS(? - ABS(users.latitude))), 2) + COS(RADIANS(?)) * COS(RADIANS(ABS(users.latitude))) * POWER(SIN(RADIANS(? - users.longitude)), 2))) AS distance
    FROM users
    HAVING distance < ?
    ', 
    [
        $lat,
        $lat,
        $lng,
        $distance
    ] 
);

$local_users = $query->num_rows() > 0
    ? $query->result()
    : NULL;

有关更多信息，请查看：http://vinsol.com/blog/2011/08/30/geoproximity-search-with-mysql/

但更好的方法是创建一个可以调用的存储过程。我在网站上的方式如下：

--
-- STORED PROCEDURE users_in_km_radius
-- 
DELIMITER $$

DROP PROCEDURE IF EXISTS users_in_km_radius $$

CREATE PROCEDURE `users_in_km_radius`( center_latitude float, center_longitude float, dist int, x_limit int, x_offset int )

BEGIN
SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;

PREPARE ps FROM 'SELECT 
    u.*, 
    6371 * 2 * ASIN(SQRT(POWER(SIN(RADIANS(? - ABS(u.latitude))), 2) + COS(RADIANS(?)) * COS(RADIANS(ABS(u.latitude))) * POWER(SIN(RADIANS(? - u.longitude)), 2))) AS distance
FROM `users` u  
WHERE u.`longitude` between ? and ? 
AND u.`latitude` between ? and ? 
HAVING distance < ? 
ORDER BY distance';

set @center_latitude = center_latitude;
set @center_longitude = center_longitude;
set @dist = dist;
set @east = center_longitude-dist/abs(cos(radians(center_latitude))*111.04);
set @west = center_longitude+dist/abs(cos(radians(center_latitude))*111.04);
set @north = center_latitude-(dist/111.04);
set @south = center_latitude+(dist/111.04);

EXECUTE ps USING @center_latitude, @center_latitude, @center_longitude, @east, @west, @north, @south, @dist;
DROP PREPARE ps;

END $$

DELIMITER ;

在CodeIgniter中使用它有点棘手：

$sql = '
    CALL users_in_km_radius( ?, ?, ? );
';

$query = $this->db->query( $sql, [ $lat, $long, $km ] ); 

if( $query->num_rows() > 0 )
{
    $result = $query->result();

    mysqli_next_result($this->db->conn_id);
    $query->free_result();
}
else
{
    $result = NULL;

    mysqli_next_result($this->db->conn_id);
    $query->free_result();
}