INSERT INTO MyGMap (id, Lat, Lng) VALUES (1,'1','2'), (2,'3','4') ON DUPLICATE KEY UPDATE id = VALUES(id), Lat=VALUES(Lat), Lng=VALUES(Lng)
UPDATE MyGMap
SET Lat = '1', Lng = '2'
WHERE Id IN (1, 2);
INSERT INTO MyGMap (Lat, Lng)
VALUES ('1', '2'), ('3', '4');
UPDATE MyGMap as row_1 INNER JOIN MyGMap as row_2
ON
row_1.id = 1 AND
row_2.id = 2
SET
row_1.Lat = '1',
row_1.Lng = '2',
row_2.Lat = '3',
row_3.Lng = '4';