【正文】 rk together to acplish an objective. For example, consider a payroll system. Its objective is paying employees. What ponents are involved? Each day， employees record their hours worked on time cards. At the end of each week, the time cards are collected and delivered to the puter center, where they are read into a payroll program. As it runs, the progra m accesses data files. Finally, the paychecks are printed and distributed. For the system to work, people, procedures, input and output media, files, hardware, and software must be carefully coordinated. Note that the program is but one ponent in a system. Computerbased systems are developed because people need information. Those people, called users, generally know what is required, but may lack the expertise to obtain it. Technical professionals, such as programmers, have the expertise, but may lack training in the user39。s basic functions. The key is keeping track of the stockonhand for each product in inventory. Inventory changes because customers purchase, exchange, and return products, so the system will have to process customer transactions. The store39。s major functions and data elements me thodically. Remember that the objective is translating user needs into technical terms. Since the system starts with the user, the first step is defining the user39。 there are dozens of alternative solutions. Let39。s major ponents have been identified .we can begin to develop them. Our system includes two programs, several pieces of equipment, and a number of data structures. During implementation, each program is planned and written using the techniques described in Chapter 7. Files are created, and their contents checked. New hardware is purchased, installed, and tested. Additionally, operating procedures are written and evaluated. Once all the ponent parts are ready, the system is tested. Assuming the user is satisfied, the finished system is released. 8 2 5 Maintenance Maintenance begins after the system is released. As people use it, they will suggest minor improvements and enhancements. Occasionally, bugs slip through debug and testing, and removing them is another maintenance task. Finally, conditions change, and a program must be updated。為使系統(tǒng)工作，人、處理過程、輸入和輸出介質(zhì)、文件、硬件和軟件都必須認(rèn)真地協(xié)調(diào)。因此他是用戶和技術(shù)專業(yè)人員之間的橋梁。對(duì)一項(xiàng)商品，該任務(wù)是容易完成的，只要計(jì)算一下手頭現(xiàn)存的貨物數(shù)量就行了。用戶應(yīng)該反復(fù)地閱讀和 修改這份書面報(bào)告。大多數(shù)用戶是按著所要完成的功能和所要處理的數(shù)據(jù)元素去思考的，目的是要區(qū)分并聯(lián)接這些關(guān)鍵的功能和數(shù)據(jù)元素，隨之產(chǎn)生邏輯系統(tǒng)設(shè)計(jì)。進(jìn)程可以是程序、過程以及能夠改變或傳送數(shù)據(jù)的任何事件．為了后續(xù)處理，數(shù)據(jù) 被保留在數(shù)據(jù)存儲(chǔ)器內(nèi)，這可用末端開口的矩形符號(hào)表示。注意，因?yàn)橛嗀洷憩F(xiàn)為某種待定的商品或某些商品在清單中的變化，所以把訂貨作為事務(wù)處理。分析員逐步地、有條理地區(qū)分了系統(tǒng)要求 輸入、存儲(chǔ)、處理、產(chǎn)生或輸出的應(yīng)該分別是哪些數(shù)據(jù)元素。 數(shù)據(jù)流程圖和數(shù)據(jù)字典是有用的工具。目標(biāo)是研究出解決問題的策略。注意，本系統(tǒng)的流程圖只說明一種可能的方案。 然而．不可能總是等到一批事務(wù)都被收集好以后再去處理。在第一個(gè)系統(tǒng)中，這兩個(gè)程序應(yīng)處理直接存取文件；在第二個(gè)系統(tǒng)中，這兩個(gè)程序應(yīng)鏈接到順序文件上。若用戶滿意了，系統(tǒng)就交付使用。 特別是對(duì)我的指導(dǎo)老師，黃孝章老師表示衷心的感謝。 讓我們?cè)谖磥?lái)的道路上越來(lái)越成功！ 。 在完成畢業(yè)設(shè)計(jì)期間，從前期的搜集資料，到最后的系統(tǒng)實(shí)施，整個(gè)設(shè)計(jì)過程讓我更深刻、更直觀地了解了管理信息系統(tǒng)分析與設(shè)計(jì)的全部流程，對(duì)管理信息系統(tǒng)的相關(guān)知識(shí)有了更進(jìn)一步的掌握。當(dāng)人們使用系統(tǒng)時(shí)，他們將提出一些小的改善和提高．有時(shí)在調(diào)試和檢測(cè)階段一些缺陷被忽略了，那么排除這些缺陷就是另一個(gè)維護(hù)任務(wù)了。數(shù)據(jù)驅(qū)動(dòng)了系統(tǒng)，所以數(shù)據(jù)結(jié)構(gòu)的選擇決定了程序的結(jié)構(gòu)。因?yàn)榉揽粘绦蛳挛缥鍟r(shí)才運(yùn)行．要等到那時(shí)才處理的思想是荒謬的。 圖 3 14 圖 4 流程圖擬訂了系統(tǒng)，突出了系統(tǒng)的主要物理部件。 數(shù)據(jù)流程圖確定了系統(tǒng)的必須具有的功能，如何才能實(shí)現(xiàn)這些功能呢？一種可能性是為每個(gè)處理過程寫一個(gè)程序；另一種可能性是把兩個(gè)或更多的處理過程合并在一個(gè)程序里，因而有幾十種可能的方案。還有，這些工具可幫助喚醒分析員的記憶。數(shù)據(jù)字典是描述和定義數(shù)據(jù)的一個(gè)數(shù)據(jù)集合，不僅在整個(gè)系統(tǒng)的分析與設(shè)計(jì)過程中有用，而且在實(shí)現(xiàn)階段經(jīng)常被用來(lái)建立數(shù)據(jù)庫(kù)。下一步該追溯該系統(tǒng)的數(shù)據(jù)流向了。最后，數(shù)據(jù)源、數(shù)據(jù)目的地、處理過程和數(shù)據(jù)存儲(chǔ)之間的數(shù)據(jù)流向用箭頭表示。因?yàn)轭櫩唾?gòu)買、換貨和退貨，所以貨單要改變，因此系統(tǒng)必須處理顧客辦理的手續(xù)。 通常，接著初步的問題定義，分析員要進(jìn)行可行性研究。分析員的目標(biāo)是確定用戶需求什么（本例中就是店主需求什么）?；镜乃枷胧且M早地抓住和修正錯(cuò)誤以及一些未理解之處。 因?yàn)槿藗冃枰畔?，所以要開發(fā)基于計(jì)算機(jī)的系統(tǒng)。對(duì)系統(tǒng)的定義略加思考，任何一個(gè)已知的計(jì)算機(jī)應(yīng)用至少包含三個(gè)部分，硬件、軟件和數(shù)據(jù)。 Process transaction and Report and reorder. In addition to the hardware and the programs, we’ll need data structures for the inventory file and for data flaws between the I/O devices and the software. Note that this system flowchart illustrates one possible solution。s memory) for example, if the analyst doesn39。s basic functions, the analyst39。 definition 2 At the end of each step, results are documented and shared with both the user and the programmers. The idea is to catch and correct errors and misunderstandings as early as possible. Perhaps the best way to illustrate the process is through example. Picture a small clothing store that purchases merchandise at wholesale