在MySQL中测量两个纬度/经度之间的距离

Question

我在mysql中有以下查询

SELECT id, 
       (SELECT ( 6371 * Acos(Cos(Radians('31.502537032937294')) * 
                             Cos(Radians(lat)) * 
                             Cos( 
                                                   Radians(lng) - Radians( 
                                                   '74.34226725250483')) 
                                     + 
                                       Sin( 
                                              Radians('31.502537032937294')) * 
                                       Sin(Radians(lat))) ) AS distance 
        FROM   `addresses` 
        WHERE  orders.id = addresses.order_id 
               AND `type` = 'from' 
               AND `address_for` = 'order' 
               AND `is_archive` = 0 
        HAVING `distance` <= 50) AS distance 
FROM   orders 
WHERE  `is_archive` = 0 
       AND `is_complete` = 0 
       AND `status_id` = 1 
       AND Date(`expected_pick_up_at`) = '2018-09-10' 

其中，我正在计算到当前位置的订单距离。该查询的结果如下

id     distance   
1027   3.392817926161619
1028   2.957290773676651

实际距离为

id     distance 

1027   0.09565605656865
1028   0.43565656101560

我用来计算距离的数据库中保存的原始经纬度为

id         lat                      long
1027       31.53189017798653        74.35203921049833
1028       31.52842855342999        74.34939790517092   

任何人都可以指导我在这方面做错了什么

注意：我还查看了以下question