From my sourcecode, I gave the information for username validation in yii framework.
<?php class User extends CActiveRecord { public static function model($className=__CLASS__) { return parent::model($className); } public function tableName() { return 'tbl_user'; } public function rules() { array('username', 'match', 'pattern' => '/^[A-Za-z0-9_]+$/u', 'message'=>'Username can contain only alphanumeric characters and hyphens(-).'), array('username','unique'), } } ?>