Syntax:
ALTER SERVER  server_name
    OPTIONS (option [, option] ...)

Alters the server information for server_name, adjusting any of the
options permitted in the CREATE SERVER statement. See [HELP CREATE
SERVER]. The corresponding fields in the mysql.servers table are
updated accordingly. This statement requires the SUPER privilege.

URL: http://dev.mysql.com/doc/refman/5.5/en/alter-server.html

