Inteiros:
UPDATE table_name SET int_column_value = int_column_value + 10;
UPDATE table_name SET int_column_value = 10 WHERE int_column_value IS NULL;
Datas:
UPDATE table_name SET date_column_value = DATEADD(date_column_value, INTERVAL 1 MONTH);
Mais informações:http:// dev.mysql.com/doc/refman/5.0/en/date-and-time-functions.html#function_adddate
