計(jì)算機(jī)畢業(yè)設(shè)計(jì)外文翻譯--電路交換網(wǎng)與vb調(diào)用數(shù)據(jù)庫-vb程序-免費(fèi)閱讀
【正文】 the closure connects Set n1 = Nothing 39。 parameter 2 Dim rstByQuery As 39。 4. The foundation orders ADO mand。 Establishes DataGrid controls the data pool = AdScore 39。 = name1 this line can be ommited = adInteger ‘ 10 外 文 原 文（二） Electric circuit exchange work and vb transfer database The result of the connection setup with circuit switching is the reservation of bandwidth all the way from the sender to the receiver. All packets follow this path. Among other properties, having all packets follow the same path means that they cannot arrive out of order. With packet switching there is no path , so different packets can follow different paths, depending on work conditions at the time they are sent. They may arrive out of order. Packet switching is more fault tolerant than circuit switching. In fact, that is why it was invented. If a switch goes down, all of the circuits using it are terminated and no more traffic can be sent on any of them. With Packet switching, packets can be routed around dead switches. Setting up a path in advance also opens up the possibility of reserving bandwidth in advance. If bandwidth is reserved, then when a packet arrives, it can be sent out immediately over the reserved bandwidth. With packet switching, no bandwidth is reserved, so packets may have to wait their turn to be forwarded. Having bandwidth reserved in advance means that no congestion can occur when a packet shows up (unless more packets show up than expected).On the other hand, when an attempt is made to establish a circuit, the attempt can fail due to congestion. Thus, congestion can occur at different times with circuit switching(at setup time) and packet switching(when packets are sent). If a circuit has been reserved for a particular user and there is no traffic to send, the bandwidth of that circuit is wasted. It cannot be used for other traffic. Packet switching does not waste bandwidth and thus is more efficient form a systemwide perspective. Understanding this tradeoff is crucial for prehending the difference between circuit switching and packet switching. The tradeoff is between guaranteed service and wasting resources versus not guaranteeing service and not wasting 11 resources. Packet switching uses storeandforward transmission. A packet is accumulated. in a router’s memory, then sent on to the next router. With circuit switching, the bits just flow through the wire continuously. The storeandforward technique adds delay. Another difference is that circuit switching is pletely transparent. The sender and receiver can use any bit rate, format, or framing method they want to. The carrier does not know or care. With packet switching, the carrier determines the basic parameters. A rough analogy is a road versus a railroad. In the former, the user determines the size, speed, and nature of the vehicle。你可以在數(shù)據(jù)庫中也可以在其他外掛程序的支持下進(jìn)行存儲過程的創(chuàng)建和調(diào)試工作。Data Source=學(xué)生信息 ″ =″selet ＊ from 學(xué)生成績 order by 成績 ″ ′ 預(yù)設(shè)好提取記錄用的 SQL 語句 Rs(1)=″select ＊ from 學(xué)生成績 where 成績 =″ ＋ Chr(34)＋ ″ 優(yōu) ″ ＋_Chr(34)＋ ″order by 成績 ″ Rs(2)=″select ＊ from 學(xué)生成績 where 成績 =″ ＋ Chr(34)＋ ″ 良 ″ ＋ _Chr(34)＋ ″order by 成績 ″ Rs(3)=″select ＊ from 學(xué)生成績 where 成績 =″ ＋ Chr(34)＋ ″ 中 ″ ＋ _Chr(34)＋ ″order by 成績 ″ Rs(4)=″select ＊ from 學(xué)生成績 where 成績 =″ ＋ Chr(34)＋ ″ 差 ″_Chr(34)＋ ″order by 成績 ″ End Sub Private Sub McScore_SeriesSelected(Series as Integer,MouseFlags as _Integer,Cancel as Integer) SelectedSeries=Series End Sub 7 Private Sub McScore_PointSelected(Series as Integer,DataPoint as_Integer,MouseFlags as Integer,Cancel as Integer) SelectedSeries=Series End Sub Private Sub McScore_Db1Click() ′ 改變 ADO 控件的記錄源并刷新 =Rs(SeletedSeries) End Sub VB 做為快速應(yīng)用開發(fā)（ RAD）工具越來越得到開發(fā)人員的認(rèn)可和接受。也由于小山上的發(fā)送器的功率太大，為了不互相干擾鄰近的系統(tǒng)不得不與它相距幾百千米。這個(gè)系統(tǒng)被安置在高層建筑上，它使用一個(gè)簡單的大的發(fā)送機(jī)并且有了用于發(fā)送和接收的簡單的通道。誰付費(fèi)誰使用，他們預(yù)先存入，比如 20或 50 euro 并且在快用完的時(shí)候可以用 PIN 碼進(jìn) 5 行再充值。然而更多的是由于美國和歐洲的基本電話數(shù)量不同。結(jié)果在整個(gè)美國就有了一 個(gè)簡單的 (模擬 )系統(tǒng)并且移動(dòng)電話開始在加利福尼亞上市同時(shí)也在紐約得到應(yīng)用。在下面的章節(jié)我們將用詳細(xì)的資料來學(xué)習(xí)這些主題。 ISPs 為家庭用戶的計(jì)費(fèi)方式基于按一個(gè)月的流量 的一半的，這是因?yàn)樗鼈冇玫孟鄬^少并且他們的顧客也很好理解這種計(jì)費(fèi)方式。用一個(gè)簡單 比喻它們就像一個(gè)是公路一個(gè)是鐵路。這種商業(yè)差別是在質(zhì)保服務(wù)和浪費(fèi)資源相對不質(zhì)保服務(wù)和不浪費(fèi)資源的。 如果帶寬被保留，那么當(dāng)一個(gè)包到達(dá)時(shí)， 通過 保留的帶寬 它可以被立即發(fā)送出去。 1 畢業(yè)設(shè)計(jì) (論文 )外文資料翻譯 專業(yè)班級： 計(jì)算機(jī)科學(xué)與技術(shù) 外文來源一： 網(wǎng)絡(luò)文摘 源碼天空 外文來源二： 指導(dǎo)教師評語：
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