protected function _wrapPrepareSql()
    {
        // set table prefix
        $quote = static::$_quote_symbol;
        $prefix_pattern = '/'.$quote.'([a-zA-Z0-9_]+)'.$quote.'(\.)'.$quote.'([a-zA-Z0-9_]+)'.$quote.'/';
        $prefix_replace = self::_quote($this->_wrapTable('$1')).'$2'.self::_quote('$3');

        $this->_prepare_sql = preg_replace($prefix_pattern, $prefix_replace, $this->_prepare_sql);
    }