query.js

query.js

function rad2deg (angle) {
    return angle * 57.29577951308232; // angle / Math.PI * 180
}

function deg2rad (angle) {
    return angle * .017453292519943295; // (angle / 180) * Math.PI;
}

function get_events (input_lat, input_lon) {
  lat = input_lat;  
  lon = input_lon;  
  rad = 3;  
  
  earth_radius = 6371;  
  

  max_lat = lat + rad2deg(rad/earth_radius);
  min_lat = lat - rad2deg(rad/earth_radius);

  max_lon = lon + rad2deg(rad/earth_radius/cos(deg2rad(lat)));
  min_lon = lon - rad2deg(rad/earth_radius/cos(deg2rad(lat)));
  

  lat = deg2rad(lat);
  lon = deg2rad(lon);
  
  sql = "SELECT *, acos(sin(lat)*sin(radians(business_latitude)) + cos(lat)*cos(radians(business_latitude))*cos(radians(business_longitude)-lon))*earth_radius As distance
    FROM (
      SELECT *
      FROM businesses
      WHERE business_latitude>min_lat AND business_latitude< max_lat
        AND business_longitude>min_lon AND business_longitude<max_lon
      ) As FirstCut 
    Where acos(sin(lat)*sin(radians(business_latitude)) + cos(lat)*cos(radians(business_latitude))*cos(radians(business_longitude)-lon))*earth_radius < rad
    GROUP BY business_id;";



}