"A good workaround is to grant a harmless privilege to the user before dropping it.  This
will create the user if it doesn't exist, so that it can be dropped safely, like so:

   GRANT USAGE ON *.* TO 'username'@'localhost';
   DROP USER 'username'@'localhost';
"

via: http://bugs.mysql.com/bug.php?id=19166

ALTER TABLE tbl_name CHANGE field_name field_name field_type;

so, to change the username field on the table user to TEXT: ALTER TABLE user CHANGE username username TEXT;

http://www.roseindia.net/sql/mysql-alter/mysql-alter-column-datatype.shtml

you need to run this query for the db:

ALTER DATABASE db_name
	CHARACTER SET utf8
	DEFAULT CHARACTER SET utf8
	COLLATE utf8_general_ci
	DEFAULT COLLATE utf8_general_ci
	;

and then these 2 queries for each table in that db:

ALTER TABLE table_name DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci;

ALTER TABLE table_name CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci;

via: http://web.archive.org/web/20070605215105/http://www.nicknettleton.com/zine/php/php-utf-8-cheatsheet

some other links that were helpful
http://www.joelonsoftware.com/articles/Unicode.html
http://stackoverflow.com/questions/140728/best-practices-in-php-and-mysql-with-international-strings

more stuff:
http://marcyes.com/2009/12/21/php_utf8_cheatsheet/

If you want to know what value your mysql currently has for a given variable, you can do in the mysql commmand line:

$ show variables where variable_name='VALUE';

so, if you want to see how long innodb will wait for a lock:

$ show variables where variable_name='innodb_lock_wait_timeout';

And to see all variables, you can:

$ show variables;