Disabling WordPress Plugins through MySQLQuery

One of my plugins is giving me problems and my site will not serve, I want to deactivate it through mysql query using this tutorial ( http://perishablepress.com/quickly-disable-or-enable-all-wordpress-plugins-via-the-database/) but when I type:

mysql> SELECT * FROM wp_options WHERE option_name = ‘active_plugins’;

I receive:

ERROR 1046 (3D000): No database selected

I’m assuming because I have 5 different databases?

How do I select the appropriate database and then deactivate a plugin?