sql 根据两点经纬度算出两点之间距离
select (sqrt( ( ((121.544685-longitude)*PI()*12656*cos(((31.134857+latitude)/2)*PI()/180)/180) * ((121.544685-longitude)*PI()*12656*cos (((31.134857+latitude)/2)*PI()/180)/180) ) + ( ((31.134857-latitude)*PI()*12656/180) * ((31.134857-latitude)*PI()*12656/180) ))/2) as distance from tblschoolsite