Update: this is more of standard connection issue. The database that turned out to be working so well was on my production image. I didn't pay close attention to the url. The development version gets the same error. I suspect I deleted it along with the XAMPP application. I can access a non-wordpress database using php with this code:
$server = 'mysql:dbname=amcolan;host=localhost:3306';
$this->id = 'root';
$this->password = 'somepassword';
parent::__construct($server,$this->id, $this->password);
This wp-config.php setup doesn't work:
/** MySQL database username */
define('DB_USER', 'root');
/** MySQL database password */
define('DB_PASSWORD', 'somepassword');
/** MySQL hostname */
define('DB_HOST', 'localhost:3306');