No need to set SQL_SAFE_UPDATES to 0, I would really discourage it to do it that way. SAFE_UPDATES is by default on for a REASON. You can drive a car without safety belts and other things if you know what I mean ;) Just add in the WHERE clause a KEY-value that matches everything like a primary-key comparing to 0, so instead of writing:
UPDATE customers SET countryCode = 'USA'
WHERE country = 'USA'; -- which gives the error, you just write:
UPDATE customers SET countryCode = 'USA'
WHERE (country = 'USA' AND customerNumber <> 0); -- Because customerNumber is a primary key you got no error 1175 any more.
Now you can be assured every record is (ALWAYS) updated as you expect.