TRIGGER based on spatial data

Question

I have a table called pano_raw that has 3 columns lat, lng, and latlng.

lat and lng are just decimals (10,3) and latlng is a spatial index of type POINT.

This is an example statement that would update the database based on lat and lng.

INSERT INTO pano_raw (latlng) VALUES( GeomFromText( 'POINT(-72.34 32.45)' ));

I'm trying to create a trigger based off the statement above, that will automatically update the column when I update lat and lng separately. It's a pain updating the spatial data column everytime with SQL since the query is specialized. It's much easier to just write a trigger (in theory) that will update when I write a simple decimal value to the table.

The problem I'm having is with the syntax. Here's my best (2 hour shot at it).

SET @sql := CONCAT('POINT(',pano_raw.lng,' ',pano_raw.lat,')');

CREATE TRIGGER trig_pano_raw BEFORE INSERT ON pano_raw
FOR EACH ROW
BEGIN
    SET pano_raw.latlng = GeomFromText( @sql ) );
END;
CREATE TRIGGER trig_pano_raw BEFORE UPDATE ON pano_raw
FOR EACH ROW
BEGIN
    SET pano_raw.latlng = GeomFromText( @sql ) );
END;

I would really appreciate help getting this working.

Answer 1

This doesn't work?

CREATE TRIGGER trig_pano_raw BEFORE INSERT ON pano_raw
FOR EACH ROW
BEGIN
    SET NEW.latlng = PointFromWKB( POINT( NEW.lat, NEW.lng ) );
END;

Regarding the Update trigger, note that

• 1st, it has to have a different name and

• 2nd, you may want to check which field is updated, like this:

update trigger

DELIMITER $$
CREATE TRIGGER trig_Update_pano_raw BEFORE UPDATE ON pano_raw
FOR EACH ROW
BEGIN
    IF ((NEW.lat != OLD.lat) OR (NEW.lng != OLD.lng))
    THEN
        SET NEW.latlng = PointFromWKB( POINT( NEW.lat, NEW.lng ) );
    ELSEIF (NEW.latlng != OLD.latlng)
    THEN
        BEGIN
            SET NEW.lat = X(NEW.latlng);
            SET NEW.lng = Y(NEW.latlng);
        END;
    END IF;
END;$$
DELIMITER ;