www.mikescher.com/www/protected/components/UserIdentity.php

<?php

/**
 * UserIdentity represents the data needed to identity a user.
 * It contains the authentication method that checks if the provided
 * data can identity the user.
 */
class UserIdentity extends CUserIdentity
{
	/**
	 * Authenticates a user.
	 * The example implementation makes sure if the username and password
	 * are both 'demo'.
	 * In practical applications, this should be changed to authenticate
	 * against some persistent user identity storage (e.g. database).
	 * @return boolean whether authentication succeeds.
	 */
	public function authenticate()
	{
		$connection = Yii::app()->db;

		$command=$connection->createCommand("SELECT SValue FROM {{othervalues}} WHERE Name = 'AdminPassword'");
		$pw = $command->queryScalar();

		$users=array(
			// username => password
			'admin' => $pw,
		);
		if(!isset($users[$this->username]))
			$this->errorCode=self::ERROR_USERNAME_INVALID;
		elseif($users[$this->username]!==$this->password)
			$this->errorCode=self::ERROR_PASSWORD_INVALID;
		else
			$this->errorCode=self::ERROR_NONE;
		return !$this->errorCode;
	}
}