mysql 按经纬度 远近距离排序

SELECT
      u.lon,
    u.lat,
   round((2 * 6378.137 * ASIN(SQRT(POW( SIN( PI()*( 29.504164- lat )/ 360 ), 2 )+ COS( PI()* 29.504164 / 180 )* COS( lat * PI()/ 180 )* POW( SIN( PI()*( 106.462176- lon )/ 360 ), 2 )))) * 1000) AS distance,
        u.id
FROM
    `user` u
ORDER BY
    distance ASC