CODEWITHSUNDEEP
mysqlstored-procedures
Kyle
Kyle

Reputation: 99

Can anyone help me with a MySQL stored procedure

I have never done one before and am trying to work through an online guide but I can't seem to find a good example of one with parameters.

CREATE PROCEDURE `calcdistance` (
    IN ulat varchar, 
    IN ulon varchar, 
    IN clat varchar, 
    IN clon varchar)
BEGIN
Select DEGREES(ACOS(SIN(RADIANS(ulat))
    * SIN(RADIANS(clat))
    + COS(RADIANS(ulat))
    * COS(RADIANS(clat))
    * COS(RADIANS(ulon - ulon))))) * 69.09 AS distance
END

the error MySQL admin gives me when I try this is:

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '  IN ulat varchar, 
    IN ulon varchar, 
    IN clat varchar, 
    IN cl' at line 2 (error 1064)

Upvotes: 0

Views: 299

Answers (3)

user247559
user247559

Reputation: 1

Great circle distance

Find the distance in kilometres between two points on the surface of the earth. This is just the sort of problem stored functions were made for. For a first order approximation, ignore deviations of the earth's surface from the perfectly spherical. Then the distance in radians is given by a number of trigonometric formulas. ACOS and COS behave reasonably:

             COS(lat1-lat2)*(1+COS(lon1-lon2)) - COS(lat1+lat2)*(1-COS(lon1-lon2)) 
rads = ACOS( --------------------------------------------------------------------- ) 
                                              2

We need to convert degrees latitude and longitude to radians, and we need to know the length in km of one radian on the earth's surface, which is 6378.388. The function:

set log_bin_trust_function_creators=TRUE; 

DROP FUNCTION IF EXISTS GeoDistKM; 
DELIMITER | 
CREATE FUNCTION GeoDistKM( lat1 FLOAT, lon1 FLOAT, lat2 FLOAT, lon2 FLOAT ) RETURNS float 
BEGIN 
  DECLARE pi, q1, q2, q3 FLOAT; 
  DECLARE rads FLOAT DEFAULT 0; 
  SET pi = PI(); 
  SET lat1 = lat1 * pi / 180; 
  SET lon1 = lon1 * pi / 180; 
  SET lat2 = lat2 * pi / 180; 
  SET lon2 = lon2 * pi / 180; 
  SET q1 = COS(lon1-lon2); 
  SET q2 = COS(lat1-lat2); 
  SET q3 = COS(lat1+lat2); 
  SET rads = ACOS( 0.5*((1.0+q1)*q2 - (1.0-q1)*q3) );  
  RETURN 6378.388 * rads; 
END; 
| 
DELIMITER ; 

-- toronto to montreal (505km): 
select geodistkm(43.6667,-79.4167,45.5000,-73.5833); 
+----------------------------------------------+ 
| geodistkm(43.6667,-79.4167,45.5000,-73.5833) | 
+----------------------------------------------+ 
|                           505.38836669921875 | 
+----------------------------------------------+

(Setting log_bin_trust_function_creators is the most convenient way to step round determinacy conventions implemented since 5.0.6.)

Source

Upvotes: -1

Sandy
Sandy

Reputation: 862

you can try 

DELIMITER $$
DROP PROCEDURE IF EXISTS calcdistance$$
CREATE PROCEDURE `calcdistance` (IN ulat VARCHAR(50), IN ulon VARCHAR(50), IN clat VARCHAR(50), IN clon VARCHAR(50))
    BEGIN
    SELECT 
    DEGREES(ACOS(SIN(RADIANS(ulat)) 
    * SIN(RADIANS(clat))
    + COS(RADIANS(ulat))
    * COS(RADIANS(clat))
    * COS(RADIANS(ulon - ulon))))
    * 69.09 AS distance;


     END$$

DELIMITER ;

Upvotes: 2

xinit
xinit

Reputation: 1916

In your query, varchar should be varchar(255). And I think that a stored procedure should end in ; by default, unless you use DELIMITER.

Upvotes: 0

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