INNER JOIN を使用して MySQL データを正しく更新するにはどうすればよいですか?

UPDATE  b
SET b.mapx = g.latitude,
    b.mapy = g.longitude
FROM business AS b
INNER JOIN business_geocode g ON b.business_id = g.business_id
WHERE (b.mapx = '' OR b.mapx = 0) AND
      g.latitude > 0

UPDATE business AS b
INNER JOIN business_geocode AS g ON b.business_id = g.business_id
SET b.mapx = g.latitude,
  b.mapy = g.longitude
WHERE  (b.mapx = '' or b.mapx = 0) and
  g.latitude > 0

CREATE TABLE business (business_id INT UNSIGNED PRIMARY KEY AUTO_INCREMENT, mapx VARCHAR(255), mapy VARCHAR(255)) ENGINE=INNODB;

CREATE TABLE business_geocode (business_geocode_id INT UNSIGNED PRIMARY KEY AUTO_INCREMENT, business_id INT UNSIGNED NOT NULL, latitude VARCHAR(255) NOT NULL, longitude VARCHAR(255) NOT NULL, FOREIGN KEY (business_id) REFERENCES business(business_id)) ENGINE=INNODB;