Update multiple rows with different columns
Something like:

INSERT INTO user (id, name, address, telephone)
VALUES
    (1, 'Tim', NULL, NULL),
    (2, NULL, 'America', '000')
ON DUPLICATE KEY UPDATE
    name = IF(ISNULL(VALUES(name)), name, VALUES(name)),
    address = IF(ISNULL(VALUES(address)), address, VALUES(address)),
    telephone = IF(ISNULL(VALUES(telephone)), telephone, VALUES(telephone))


will work (leaving the NULL fields untouched), presuming the id field is the primary key and will trigger the DUPLICATE KEY UPDATE, although I can't comment on how efficient it would be.