mysql 函式

DROP FUNCTION IF EXISTS func_calcDistance；
CREATE FUNCTION func_calcDistance(
    origLng DECIMAL(20,6),
    origLat DECIMAL(20,6),
    longitude DECIMAL(20,6),
    latitude DECIMAL(20,6)
)
RETURNS DOUBLE
BEGIN
    DECLARE result DOUBLE DEFAULT 0;
    SET result = round(6378.138*2*asin(
    sqrt(pow(sin((origLat*pi()/180
 
-latitude*pi()/180)/2),2)+
    cos(origLat*pi()/180)*cos(latitude*pi()/180)*pow(sin((origLng*pi()/180-longitude*pi()/180)/2),2)))*1000);
    RETURN result;
END;

IN RUBY MIGRATION

  ActiveRecord::Base.connection.execute <<-SQL
      DROP FUNCTION IF EXISTS func_calcDistance；
        CREATE FUNCTION func_calcDistance(
            origLng DECIMAL
 
(20,6),
            origLat DECIMAL(20,6),
            longitude DECIMAL(20,6),
            latitude DECIMAL(20,6)
        )
        RETURNS DOUBLE
        BEGIN
            DECLARE result DOUBLE DEFAULT 0;
            SET result = round(6378.138*2*asin(
            sqrt(pow(sin((origLat*pi()/180-latitude*pi()/180
 
)/2),2)+cos(origLat*pi()/180)*cos(latitude*pi()/180)*pow(sin((origLng*pi()/180-longitude*pi()/180)/2),2)))*1000);
            RETURN result;
        END
  SQL

  LastestDeviceLocation.select("func_calcDistance() as distance").order("distance")