public function _prepare($sql)
    {
        $connection = $this->_adapter->getConnection();

        // db2_prepare on i5 emits errors, these need to be
        // suppressed so that proper exceptions can be thrown
        $this->_stmt = @db2_prepare($connection, $sql);

        if (!$this->_stmt) {
            /**
             * @see Zend_Db_Statement_Db2_Exception
             */
            // require_once 'Zend/Db/Statement/Db2/Exception.php';
            throw new Zend_Db_Statement_Db2_Exception(
                db2_stmt_errormsg(),
                db2_stmt_error()
            );
        }
    }