/**
  * Inserts a new row.
  *
  * Columns must be in underscore format.
  * 
  * @param array $data Column-value pairs.
  * @param string $where An SQL WHERE clause.
  * @return int The last insert ID.
  */
 public function insert(&$data)
 {
     $this->_db->insert($this->_name, $data);
     return $this->_db->lastInsertId($this->_name, $this->_primary);
 }