【正文】 維護延續(xù)在系統(tǒng)的整個生命期 內(nèi)。 實現(xiàn) 系統(tǒng)的主要部分一分析清楚了，就 能開始開發(fā)這幾部分。一般來說，這些事務(wù)處理系統(tǒng)要求直接存取文件。利用這些數(shù)據(jù)元素能安排文件的數(shù)據(jù)結(jié)構(gòu)。最后，貨物清單文件由一個 Report and reorder（報告和再訂貨）程序處理。 設(shè)計 當進入設(shè)計階段的時候，已知道必須做什么事。用戶只是從功能和數(shù)據(jù)出發(fā)考慮系統(tǒng)，他們并不具體設(shè)計程序、文件、和硬件，并且在這個初始的帶有決定性的分析階段，分析員必須像用戶而不像程序設(shè)計員一樣去思考問題。例如，某種已知貨物的現(xiàn)存量就是由某個處理過程中的某種算法產(chǎn)生出來的。注意，因為訂貨表現(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。為了后續(xù)處理，數(shù)據(jù)被存儲可以是磁盤文件、磁帶文件、數(shù)據(jù)庫、一些筆記或者甚至是人的記憶。店主希望有選擇地查看供應(yīng)中任意一種短缺商品的清單，如果合理的話，定貨補充庫存，因此系統(tǒng)必須能和經(jīng)營管理部門對話。該研究是整個系統(tǒng)分析和設(shè)計一個簡略的方案 ,應(yīng)力圖回答以下三個問題 : 1. 問題能解決嗎 ? 沙隴中學八年級語文科期末考試模擬試卷（中） 14 2. 在用戶的環(huán)境下問題能解決嗎 ? 合適的花費上問題能解決嗎 ? 如果這些問題中的任何一個得到的是否定回答 ,那么該系統(tǒng)就不應(yīng)開發(fā)。注意，當這個過程開始時，用戶擁有很重要的資料，分析員必須認真地聽和學。 設(shè)想一個小服裝店，成批的購買貨物 ,所貨物擺在貨架上 , 零售給顧客。被稱為用戶的那些人常常知道需求什么信息，但是他們可能缺乏得到這些信息的計算機的專門知識。僅僅編寫程序是不夠的，因為程序只是系統(tǒng)中的一部分。系統(tǒng)的界面是運用 vb軟件制作的，以上幾個模塊都是運用 vb 控件綁定的方法來實現(xiàn)對后臺數(shù)據(jù)庫的連接，后臺數(shù)據(jù)庫大概分為以下幾個表：專業(yè)信息表，收費類別表，學生職務(wù)表，學生信息表，學生政治面貌表，用戶登入表。本系統(tǒng)針對學校 ,經(jīng)過實際的需求分析，采用功能強大的 作為開發(fā)工具來開發(fā)學生信息管 理系統(tǒng)。 in the second system, they would be linked to sequential files. A program to process direct access data is different from a program to process sequential data. The data drive the system. The choice of a data structure determines the program’s structure. Note that the program is defined and planned in the context of the system. Implementation Once the system’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. Summary A system is a collection of hardware, software, data, and procedural ponents that work together to acplish an objective. A program is but one ponent in a system. System are planned and designed by system analysts who generally follow a welldefined, 沙隴中學八年級語文科期末考試模擬試卷（中） 10 methodical process. The first step in the process is problem definition, when the analyst attempts to discover exactly what the user needs. Often, following a preliminary problem definition, a feasibility study is conducted to determine if the problem can be solved. Given a clear problem definition, analysis begins. During this stage, the analyst develops a logical model of the system. Key functions are linked through a data flow diagram. Using the diagram as a tool, the data flows are traced, and the system’s data elements are identified and recorded in a data dictionary. After the logical system is reviewed with the user, design begins. During design, the analyst develops a model of the physical system. A system flowchart can be used to map the system, defining each physical ponent as a symbol. A good systems analyst considers a number of alternative solutions to the problem before settling on one. Implementation follows design. Programs are planned and written。 thus, product and reorder quantities must be stored in 沙隴中學八年級語文科期末考試模擬試卷（中） 7 STOCK. Other data elements, such as purchased and the purchase quantity, are generated by CUSTOMER. Still others, for example selling price and reorder point, are generated by or needed by MANAGEMENT. The current stock –onhand for a given item is an example of a data element generated by an algorithm in one of the procedures. Step by step, methodically, the analyst identifies the data elements to be input to, stored by, manipulated by, generated by, or output by the system. To keep track of the data elements, the analyst might list each one in a data dictionary. A simple data dictionary can be set up on index cards, but puterized data dictionaries have bee increasingly popular. The data dictionary, a collection of data describing and defining the data, is useful throughout the systems analysis and design process, and is often used to build a database during the implementation stage. The idea of analysis is to define the system’s major functions and data elements methodically. Remember that the objective is translating user needs into technical terms. Since the system starts with the user, the first step is defining the user’s needs. Users think in terms of functions and data. They do not visualize programs, or files, or hardware, and during this initial, crucial analysis stage, it is essential that the analyst think like a user, not like a programmer. Data flow diagrams and data dictionaries are useful tools. They provide a format for recording key information about the proposed system. Also, they jog the analyst’s memory。 information is huge, it makes the management of the information bee a plicated and tedious work. This system aims at the school, passing by practically of demand analysis, adopt mighty to develop the student information management 沙隴中學八年級語文科期末考試模擬試卷（中） 2 system. The whole system design process follow the principle of simple operation, beautiful and vivid interface and practical request. The student information management system including the function of system management, basic information management, study management, prize and punishment management , print statement and so on. Through the proof of using, the student information managem