Question

When I attempt to cast my FLOATS into CHARS in this procedure, I get null values in the database. Location is a Geospatial field. What am I doing wrong?

CREATE DEFINER=`me`@`%` PROCEDURE `UpdateLocationByObjectId`(IN objectId INT, 
                                            IN latitude FLOAT,
                                            IN longitude FLOAT)
BEGIN
    UPDATE Positions P
    JOIN Objects O ON P.Id = O.PositionId 
        SET P.Location = GeomFromText('Point(' + CAST(latitude AS CHAR(10)) + ' ' + CAST(longitude AS CHAR(10)) +')')
        WHERE O.ObjectId = objectId;
END

If I use this as a test, it works fine.

CREATE DEFINER=`me`@`%` PROCEDURE `UpdateLocationByObjectId`(IN objectId INT, 
                                            IN latitude FLOAT,
                                            IN longitude FLOAT)
BEGIN
    UPDATE Positions P
    JOIN Objects O ON P.Id = O.PositionId 
        SET P.Location = GeomFromText('Point(10 10')')
        WHERE O.ObjectId = objectId;
END

Answer 1

Change this line

SET P.Location = GeomFromText('Point(' + CAST(latitude AS CHAR(10)) + ' ' 
                                       + CAST(longitude AS CHAR(10)) +')')

To

SET P.Location = GeomFromText(concat('Point(' , CAST(latitude AS CHAR(10)) , ' ' 
                                              , CAST(longitude AS CHAR(10)) ,')'))

The + operator is adding your text values (’10’ + ’10’) = 20
So the center part evaluates to ‘Point(‘ + 20 + ‘)’, adding text that cannot be read as number + numbers evaluates to NULL.

Only the concat function can concatenate strings.
In fact this code will work just as well:

SET P.Location = GeomFromText(concat('Point(', latitude, ' ', longitude,')'))