protected function fix_table_names($sql)
    {
        if (!$this->options['table_prefix']) {
            return $sql;
        }

        $sql = parent::fix_table_names($sql);

        // replace sequence names, and other Oracle-specific commands
        $sql = preg_replace_callback('/((SEQUENCE ["]?)([^" \r\n]+)/',
            array($this, 'fix_table_names_callback'),
            $sql
        );

        $sql = preg_replace_callback(
            '/([ \r\n]+["]?)([^"\' \r\n\.]+)(["]?\.nextval)/',
            array($this, 'fix_table_names_seq_callback'),
            $sql
        );

        return $sql;
    }