-- Unique key for table must be pre-defined
INSERT INTO `tableName`
VALUES (field1,field2,field3,'-1',...,fieldN,'0')
ON DUPLICATE KEY
UPDATE `field1` = 'abc', `field2` = '123'

http://www.apphp.com/index.php?snippet=mysql-insert-or-update-if-unique-key-already-exists

This snippet allows you to insert new record into table. In case a unique key already exists - it updates appropriate fields only, leaving other fields untouched.

Insert or Update Record if Unique Key Already Exists

mysql

SQL