【正文】 新月異的變化，特別是計(jì)算機(jī)的應(yīng)用及普及到經(jīng)濟(jì)和社會(huì)生活的各個(gè)領(lǐng)域。 數(shù)據(jù)庫的特點(diǎn)： 4.避免了數(shù)據(jù)不一致性 。重點(diǎn)的說明了系統(tǒng)設(shè)計(jì)的重點(diǎn)、設(shè)計(jì)思想、難點(diǎn)技術(shù)和解決方案 。而對(duì)于后者則要求應(yīng)用程序功能完備 ,易使用等特點(diǎn)。 系統(tǒng)的核心是 添加 、 修改 和 刪除 三者之間的聯(lián)系，每一個(gè)表的修改都將聯(lián)動(dòng)的影響其它的表，當(dāng)完成 添加 或 刪除 操作時(shí)系統(tǒng)會(huì)自動(dòng)地完成 學(xué)生信息 的修改。數(shù)據(jù)庫技術(shù)是數(shù)據(jù)管理的技術(shù)，它隨著數(shù)據(jù)管理任務(wù)的需要而產(chǎn)生于 20世紀(jì) 60年代中期。它已經(jīng)被應(yīng)用于許多領(lǐng)域，計(jì)算機(jī)之所以如此流行的原因主要有以下幾個(gè)方面： 首先，計(jì)算機(jī)可以代替人工進(jìn)行許多繁雜的勞動(dòng)； 其次，計(jì)算機(jī)可以節(jié)省許多資源； 第三，計(jì)算機(jī)可以大大的提高人們的工作效率； 第四，計(jì)算機(jī)可以使敏感文檔更加安全，等等。這大大地阻礙了人類經(jīng)濟(jì)的發(fā)展。 設(shè)計(jì)一個(gè)數(shù)據(jù)庫系統(tǒng)，首先必須確認(rèn)數(shù)據(jù)庫系統(tǒng)的用戶和用途。需求分析的結(jié)果整理成需求分析說明書，這是數(shù)據(jù)庫技術(shù)人員與應(yīng)用組織部門的工作人員取得共識(shí)的基礎(chǔ) ，必須得到有關(guān)組織部門人員的確認(rèn)。由于管理人員與數(shù)據(jù)庫系統(tǒng)設(shè)計(jì)者之間存在著這樣的距離，所以需要管理部門和數(shù)據(jù)庫系統(tǒng)設(shè)計(jì)者更加緊密地配合，充分提供有關(guān)信息和資料，為數(shù)據(jù)庫系統(tǒng)的設(shè)計(jì)打下良好的基礎(chǔ)。從訪問中，可獲得有關(guān)該組織高層管理活動(dòng)和決策過程的信息需求、該組織的運(yùn)行政策、未來發(fā)展變化趨勢(shì)等與戰(zhàn)略規(guī)劃有關(guān)的信息。 原始輸入 篩選后的 查找結(jié)果 格式化的輸出 圖 下面是學(xué)生信息管理數(shù)據(jù)庫系統(tǒng)設(shè)計(jì)的業(yè)務(wù)流程分析，原始的數(shù)據(jù)是學(xué)生的輸入處理 查找分析 輸出處理 信息，系統(tǒng)要求統(tǒng)計(jì)學(xué)生的信息，并根據(jù)信息統(tǒng)計(jì)的結(jié)果由獎(jiǎng)學(xué)金評(píng)委評(píng)選出獲得獎(jiǎng)學(xué)金的學(xué)生，其數(shù)據(jù)流圖如下圖 信息清單 統(tǒng)計(jì)整理 報(bào)表清單 獲獎(jiǎng)清單 存儲(chǔ)文件 圖 數(shù)據(jù)流圖 ER 圖設(shè)計(jì) ER 圖設(shè)計(jì)模式分為兩種： 一種是以局部 ER 圖為基礎(chǔ)設(shè)計(jì)全局模式，稱為 集中式模式設(shè)計(jì)； 另一種是先設(shè)計(jì)局部 ER模型圖，再由若干個(gè)局部 ER模型圖綜合成為全局ER 模型圖，稱為 綜合設(shè)計(jì)法。局部實(shí)體集的產(chǎn)生包括確定局部實(shí)體集的屬性和鍵碼。同時(shí)，局部實(shí)體集間的聯(lián)系也需要滿足局部應(yīng)用的各種要求。在 Visual Basic 環(huán)境下，利用事件驅(qū)動(dòng)的編程機(jī)制、新穎易用的可視化設(shè)計(jì)工具，使用 Windows 內(nèi)部的應(yīng)用程序接口 (API)函數(shù)，以及動(dòng)態(tài)鏈接庫 (DLL)、動(dòng)態(tài)數(shù)據(jù)交換 (DDE)、對(duì)象的鏈接與嵌入 (OLE)、開放式數(shù)據(jù)訪問 (ODBC)等技術(shù)，可以高效、快速地開發(fā)出 Windows 環(huán)境下功能強(qiáng)大、圖形界面豐富的應(yīng)用軟件系統(tǒng)。在一般的面向?qū)ο蟪绦蛟O(shè)計(jì)語言中，對(duì)象由程序代碼和數(shù)據(jù)組成，是抽象的概念；而 Visual Basic 則是應(yīng)用面向?qū)ο蟮某绦蛟O(shè)計(jì)方法 (OOP)，把程序和數(shù)據(jù)封裝起來作為一個(gè)對(duì)象，并為每個(gè)對(duì)象賦予應(yīng)有的屬性，使對(duì)象成為實(shí)在的東西。一個(gè)對(duì)象可能會(huì)產(chǎn)生多個(gè)事件，每個(gè)事件都可以通過一段程序來響應(yīng)。 動(dòng)態(tài)數(shù)據(jù)交換 (DDE) 利用動(dòng)態(tài)數(shù)據(jù)交換 (Dynamic Data Exchange)技術(shù)，可以把一種應(yīng)用程序中的數(shù)據(jù)動(dòng)態(tài)地鏈接到另一種應(yīng)用程序中，使兩種完全不同的應(yīng)用程序建立起一條動(dòng)態(tài)數(shù)據(jù)鏈路。此外，通過動(dòng)態(tài)鏈接庫，還可以調(diào)用 Windows 應(yīng)用程序接口 (API)函數(shù)，實(shí)現(xiàn) SDK 所具有的功能。 Access 也提供了數(shù)據(jù)存儲(chǔ)庫，可以使用桌面數(shù)據(jù)庫文件把數(shù)據(jù)庫文件置于網(wǎng)絡(luò)文件服務(wù)器，與其他網(wǎng)絡(luò)用戶共享數(shù)據(jù)庫。一個(gè)記錄集合是動(dòng)態(tài)的也就意味著，當(dāng)原來的數(shù)據(jù)表中的容改變了以后，該記錄集合中的記錄也會(huì)隨之改變。 您可以使用 Visual Basic 的 Application Wizard 也可以使用 Visual Basic 的菜單編輯器建立菜單或者修改已經(jīng)存在的菜單。在 “ 控件 ” 選項(xiàng)卡列表中選擇 “Microsoft Windows Common Controls ” 后工具相中增加改控件。微軟的 Help 是一套獨(dú)立于 Visual Basic 的用來協(xié)助我們創(chuàng)建、運(yùn)行于 32位 Windows 操作系統(tǒng)下的幫助文件的工具。同時(shí)， Inter 技術(shù)提供了一種向用戶發(fā)布數(shù)據(jù)庫內(nèi)容的標(biāo)準(zhǔn)化的訪問方法。最近，由于數(shù)據(jù)庫的普及，數(shù)據(jù)庫技術(shù)已經(jīng)被應(yīng)用到了 新的領(lǐng)域，諸如用于Inter 的數(shù)據(jù)庫或用于公司內(nèi)聯(lián)網(wǎng)的數(shù)據(jù)庫。數(shù)據(jù)管理技術(shù)的優(yōu)劣，將直接影響數(shù)據(jù)處理的效率。 圖 最后一步就是要選擇一個(gè)要保存數(shù)據(jù)庫文件的名字和位置。建立數(shù)據(jù)庫連接對(duì)像 DBpath = amp。上用到了三個(gè)變量 conn,Dbpath,rs。通過這一模塊，可以實(shí)現(xiàn)學(xué)生基本情況的添加、刪除、更新。 (6)個(gè)人信息查詢 通過輸入學(xué)號(hào)便可以查詢到這個(gè)學(xué)生的全部信息，包括姓名、性別、生日是、班號(hào)、入學(xué)日期、聯(lián)系電話、獎(jiǎng)懲日期、獎(jiǎng)懲名稱和成績(jī)表都一目了然，很大的方便了教工們查詢學(xué)生信息的過程。該種風(fēng)格特點(diǎn)是列標(biāo)題緊挨著數(shù)據(jù)列在此窗口還可以增加新學(xué)生紀(jì)錄。通過使用由 Visual Basic 提供的專用的直 接與數(shù)據(jù)庫相連的接口 結(jié) 束 語 經(jīng)過一個(gè)多月的設(shè)計(jì)和開發(fā)，學(xué)生信息管理系統(tǒng)基本開發(fā)完畢。 另外，在系統(tǒng)開發(fā)過程中劉老師的助手屈會(huì)鋒同學(xué)也給于我很大的幫助，幫助解決了不少的難點(diǎn)，使得系統(tǒng)能及時(shí)開發(fā)完成，還有同組的同學(xué)同樣給與我不少幫助，這里一并表示感謝。t admit even to himself that there were some things other people could do better. If you kept beating him at anything you had to be cheating. He started a nasty argument over it one nightcould have gotten seriousbut Gerard and Caine broke it up. G ive Caine that. He took my part that time. Poor guy . . . Hell of a way to go, you know? His throat . . . Well, anyhow, there I was in Texorami, making music and women, winning at cards and jockeying around the sky. Palm trees and nightblooming wallflowers. Lots of good port smellsspices, coffee, tar, saltyou know. Gentlefolk, merchants, and peons the same straights as in most other places. Sailors and assorted travelers passing in and out. Guys like me living around the edges of things. I spent a little over two years in Texorami, happy. Really. Not much contact with the others. Sort of postcard like hellos via the Trumps every now and then, and that was about it. Amber was pretty much off my mind. All this changed one night when I was sitting there with a full house and the guy across from me was trying to make up his mind whether or not I was bluffing. The Jack of Diamonds began talking to me. Yes, that is how it started. I was in a weird frame of mind anyway. I had just finished a couple very hot sets and was still kind of high. A lso, I was physically strung out from a long day39。t answering, he wasn39。s what I meant about gliding it being a bit different. So, I bore to the west till the woods gave way to surface green, which quic kly faded, dispersed, broke to brown, tan, yellow. L ight an d crumbly then, splotched. The price of that was a storm. I rode it out as much as I could, till the lightnings for ked nearby and I feared that the gusts were getting to be too much for the little glider. I toned it dow n fast then, but got more green below as a result. Still, I pulled it out of the storm with a yellow sun firm and bright at my back. After a time, I got it to go desert beneath me again, stark and rolling. Then the sun shrank and strands of cloud whipped past its face, erasing it bit by bit. That was the shortcut that took me farther from Amber than I had been in a long while. No sun then, but the light remained, just as bright but eerie now, directionless. It tricked my eyes, it screwed up perspective. I dropped lower, limiting my range of vision. Soon large rocks came into view, and I fought for the shapes I remembered. Gradually, these occurred. The buc kling, flowing effect was easier to achieve under these conditions, but its production was physically disconcerting. I t made it even more difficult to judge my effectiveness in guiding the glider. I got lower than I thought I was and almost collided with one of the roc ks. Finally, though, the smokes rose and flames danced about as I remembered them conforming to no particular pattern, just emerging here and there from crevasses, holes, cave mouths. Colors began to misbehave as I recalled from my brief view. Then came the actual motion of the rocksdrifting, sailing, like rudderless boats in a place where they wring out rainbows. By then, the air currents had gone crazy. One updraft after another, like fountains, I fought them as best I could, but knew I could not hold things together much longer at that altitude. I rose a considerable distance