public function enqueueStatement(CNabuDBAbstractStatement $statement)
    {
        if ($statement instanceof CMySQLStatement) {
            $hash = $statement->getHash();
            if (!is_array($this->statements) || count($this->statements) === 0) {
                $this->statements = array($hash => $statement);
            } else {
                $this->statements[$hash] = $statement;
            }
        }
    }