計(jì)算機(jī) 軟件工程 外文文獻(xiàn) 外文翻譯 英文文獻(xiàn) 數(shù)據(jù)庫開發(fā)過程

1、英文原文版出處： a.ghatak,k.thyagaraian,comtemperary optic,plenum press,1978 譯文：數(shù)據(jù)庫開發(fā)過程 基于信息工程的信息系統(tǒng)規(guī)劃是數(shù)據(jù)庫開發(fā)項(xiàng)目的一個(gè)來源。這些開發(fā)新數(shù)據(jù)庫的項(xiàng)目通常是為了滿足組織的戰(zhàn)略需求，例如改善客戶支持、提高產(chǎn)品和庫存管理或進(jìn)行更精確的銷售預(yù)測。然而許多數(shù)據(jù)庫開發(fā)項(xiàng)目更多的是以自底向上的方式出現(xiàn)的，例如信息系統(tǒng)的用戶需要特定的信息來完成他們的工作，從而請求開始一個(gè)項(xiàng)目，又如其他信息系統(tǒng)的專家發(fā)現(xiàn)組織需要改進(jìn)數(shù)據(jù)管理而開始新的項(xiàng)目。即使在自底向上的情況下，建立企業(yè)數(shù)據(jù)模型也是必須的，以便理解現(xiàn)有的數(shù)據(jù)庫是否可以提供所

2、需的數(shù)據(jù)，否則，新的數(shù)據(jù)庫、數(shù)據(jù)實(shí)體和屬性都應(yīng)該加到當(dāng)前的組織數(shù)據(jù)資源中去。 無論是戰(zhàn)略需求還是操作信息的需求，每個(gè)數(shù)據(jù)庫開發(fā)項(xiàng)目通常集中在一個(gè)數(shù)據(jù)庫上。一些數(shù)據(jù)庫項(xiàng)目僅僅集中在定義、設(shè)計(jì)和實(shí)現(xiàn)一個(gè)數(shù)據(jù)庫，以作為后續(xù)信息系統(tǒng)開發(fā)的基礎(chǔ)。然而在大多數(shù)情況下，數(shù)據(jù)庫及其相關(guān)信息處理功能是作為一個(gè)完整的信息系統(tǒng)開發(fā)項(xiàng)目的一部分而被開發(fā)的。一. 系統(tǒng)開發(fā)生命周期 指導(dǎo)管理信息系統(tǒng)開發(fā)項(xiàng)目的傳統(tǒng)過程是系統(tǒng)開發(fā)生命周期(sdlc)。系統(tǒng)開發(fā)生命周期是指一個(gè)組織中由數(shù)據(jù)庫設(shè)計(jì)人員和程序員組成的信息系統(tǒng)專家小組詳細(xì)說明、開發(fā)、維護(hù)和替換信息系統(tǒng)的全部步驟。這個(gè)過程比作瀑布是因?yàn)槊恳徊蕉剂鞯较噜彽南乱徊?，即信?/p>

3、系統(tǒng)的規(guī)格說明是一塊一塊地開發(fā)出來的，每一塊的輸出是下一塊的輸入。然而如圖所示，這些步驟并不是純線性的，每個(gè)步驟在時(shí)間上有所重疊（因此可以并行地管理步驟），而且當(dāng)需要重新考慮先前的決策時(shí)，還可以回滾到前面某些步驟。（因而水可以在瀑布中倒流?。┫到y(tǒng)開發(fā)生命周期的每一階段都包括與數(shù)據(jù)庫開發(fā)相關(guān)的活動，所以，數(shù)據(jù)庫管理的問題遍布整個(gè)系統(tǒng)開發(fā)過程。請注意，系統(tǒng)開發(fā)生命周期的階段和數(shù)據(jù)庫開發(fā)步驟之間不存在一一對應(yīng)的關(guān)系，概念數(shù)據(jù)建模發(fā)生在兩個(gè)系統(tǒng)開發(fā)生命周期階段之間。1.1 企業(yè)建模 數(shù)據(jù)庫開發(fā)過程從企業(yè)建模（系統(tǒng)開發(fā)生命周期中項(xiàng)目論證和選擇階段的一部分）開始，設(shè)定組織數(shù)據(jù)庫的范圍和一般內(nèi)容。企業(yè)建模發(fā)

4、生在信息系統(tǒng)規(guī)劃和其他活動期間，這些活動確定信息系統(tǒng)的哪個(gè)部分需要改變和加強(qiáng)并概述出全部組織數(shù)據(jù)的范圍。在這一步中，檢查當(dāng)前數(shù)據(jù)庫和信息系統(tǒng)，分析作為開發(fā)項(xiàng)目主體的業(yè)務(wù)領(lǐng)域的本質(zhì)，用非常一般的術(shù)語描述每個(gè)信息系統(tǒng)在開發(fā)時(shí)所需要的數(shù)據(jù)。每個(gè)項(xiàng)目只有當(dāng)它達(dá)到組織的預(yù)期目標(biāo)時(shí)才可以進(jìn)行下一步。1.2 概念數(shù)據(jù)建模 對一個(gè)已經(jīng)開始的信息系統(tǒng)項(xiàng)目而言，概念數(shù)據(jù)建模階段分析信息系統(tǒng)的全部數(shù)據(jù)需求。它分為兩個(gè)階段。首先，它在項(xiàng)目開始和規(guī)劃階段建立一張圖。同時(shí)建立其他文檔來概述不考慮現(xiàn)存數(shù)據(jù)庫的情況下特定開發(fā)項(xiàng)目中所需的數(shù)據(jù)范圍。此時(shí)僅僅包括高層類別的數(shù)據(jù)（實(shí)體）和主要聯(lián)系。然后在系統(tǒng)開發(fā)生命周期的分析階段產(chǎn)

5、生確定信息系統(tǒng)必須管理的全部組織數(shù)據(jù)的詳細(xì)數(shù)據(jù)模型，定義所有數(shù)據(jù)屬性，列出全部數(shù)據(jù)類別，表示數(shù)據(jù)實(shí)體間所有的業(yè)務(wù)聯(lián)系，確定描述數(shù)據(jù)完整性的全部規(guī)則。在分析階段，還要檢查概念數(shù)據(jù)模型（在后面也稱作概念模式）與用來解釋目標(biāo)信息系統(tǒng)其他方面的模型類別的一致性，例如處理步驟、處理數(shù)據(jù)的規(guī)則以及時(shí)間的時(shí)序。然而，即使是這樣詳細(xì)的概念數(shù)據(jù)模型也只是初步的，因?yàn)楹罄m(xù)的信息系統(tǒng)生命周期中的活動在設(shè)計(jì)事務(wù)、報(bào)表、顯示和查詢時(shí)可能會發(fā)現(xiàn)遺漏的元素或錯(cuò)誤。因此，經(jīng)常說到的概念數(shù)據(jù)建模是以一種自頂向下的方式完成的，它由業(yè)務(wù)領(lǐng)域的一般理解所驅(qū)動，而不是由特定的信息處理活動所驅(qū)動。1.3 邏輯數(shù)據(jù)庫設(shè)計(jì) 邏輯數(shù)據(jù)庫設(shè)計(jì)從

6、兩個(gè)角度進(jìn)行數(shù)據(jù)庫開發(fā)。首先，將概念數(shù)據(jù)模型變換成基于關(guān)系數(shù)據(jù)庫理論的標(biāo)準(zhǔn)表示方法關(guān)系。然后像設(shè)計(jì)信息系統(tǒng)的每個(gè)計(jì)算機(jī)程序（包括程序的輸入和輸出格式）那樣，對數(shù)據(jù)庫支持的事務(wù)、報(bào)表、顯示和查詢進(jìn)行詳細(xì)的檢查。在這個(gè)所謂的自底向上的分析中，精確地驗(yàn)證數(shù)據(jù)庫中需要維護(hù)的數(shù)據(jù)和在每個(gè)事務(wù)、報(bào)表等等中需要的那些數(shù)據(jù)的性質(zhì)。 對于每個(gè)單獨(dú)的報(bào)表、事務(wù)等等的分析都要考慮一個(gè)特定的、有限制的但是完全的數(shù)據(jù)庫視圖。當(dāng)報(bào)表、事務(wù)等被分析時(shí)有可能根據(jù)需要而改變概念數(shù)據(jù)模型。尤其在大型的項(xiàng)目中，不同的分析人員和系統(tǒng)開發(fā)者的團(tuán)隊(duì)可以獨(dú)立地工作在不同的程序或程序集中，他們所有工作的細(xì)節(jié)直到邏輯設(shè)計(jì)階段才可能會顯示出來。

7、在這種情況下，邏輯數(shù)據(jù)庫設(shè)計(jì)階段必須將原始的概念數(shù)據(jù)模型和這些獨(dú)立的用戶視圖合并或集成到一個(gè)全面的設(shè)計(jì)中。在進(jìn)行邏輯信息系統(tǒng)設(shè)計(jì)時(shí)也可以確定額外的信息處理需求，此時(shí)這些新的需求必須集成到前面確定的邏輯數(shù)據(jù)庫設(shè)計(jì)中。 邏輯數(shù)據(jù)庫設(shè)計(jì)的最后一步是根據(jù)為生成結(jié)構(gòu)良好的數(shù)據(jù)規(guī)格說明而確定的規(guī)則，將組合的、協(xié)商后的數(shù)據(jù)規(guī)格說明轉(zhuǎn)換成基本的或原子的元素。對當(dāng)今的大部分?jǐn)?shù)據(jù)庫而言，這些規(guī)則來自關(guān)系數(shù)據(jù)庫理論和稱作規(guī)范化的過程。這一步的結(jié)果是產(chǎn)生管理這些數(shù)據(jù)的、不引用任何數(shù)據(jù)庫管理系統(tǒng)的完整的數(shù)據(jù)庫描述圖。在完成邏輯數(shù)據(jù)庫設(shè)計(jì)后，開始確定詳細(xì)的計(jì)算機(jī)程序的邏輯和維護(hù)、報(bào)告數(shù)據(jù)庫內(nèi)容所需的查詢。1.4 物理數(shù)據(jù)

8、庫設(shè)計(jì)和定義 物理數(shù)據(jù)庫設(shè)計(jì)和定義階段決定計(jì)算機(jī)存儲器（通常是磁盤）中數(shù)據(jù)庫的組織，定義數(shù)據(jù)庫管理系統(tǒng)的物理結(jié)構(gòu)，概述處理事務(wù)的程序，產(chǎn)生期望的管理信息和決策支持的報(bào)表。本階段的目標(biāo)是設(shè)計(jì)能夠有效、安全地管理所有數(shù)據(jù)處理的數(shù)據(jù)庫，因此物理數(shù)據(jù)庫設(shè)計(jì)需緊密結(jié)合物理信息系統(tǒng)其他方面的設(shè)計(jì)，包括程序、計(jì)算機(jī)硬件、操作系統(tǒng)和數(shù)據(jù)通信網(wǎng)絡(luò)。1.5 數(shù)據(jù)庫實(shí)現(xiàn) 數(shù)據(jù)庫實(shí)現(xiàn)階段編寫、測試和安裝處理數(shù)據(jù)庫的程序。設(shè)計(jì)人員可以使用標(biāo)準(zhǔn)的編程語言（如cobol、c或visual basic）、專用的數(shù)據(jù)庫處理語言（如sql），或?qū)Ｓ玫姆沁^程化語言來編程，以產(chǎn)生固定格式的報(bào)表、顯示結(jié)果，可能還包括圖表。在實(shí)現(xiàn)階段，

9、還要完成所有的數(shù)據(jù)庫文檔，培訓(xùn)用戶，為信息系統(tǒng)（和數(shù)據(jù)庫）的用戶安裝程序。最后一步是利用現(xiàn)存的信息源（遺留應(yīng)用中的文件和數(shù)據(jù)庫以及現(xiàn)在需要的新數(shù)據(jù)）加載數(shù)據(jù)。加載數(shù)據(jù)的第一步經(jīng)常是將數(shù)據(jù)從現(xiàn)存的文件和數(shù)據(jù)庫中轉(zhuǎn)到一種中間的格式（如二進(jìn)制或文本文件），然后再將這些中間數(shù)據(jù)加載到新的數(shù)據(jù)庫中。最后，運(yùn)行數(shù)據(jù)庫以及相關(guān)的應(yīng)用以供實(shí)際的用戶維護(hù)和檢索數(shù)據(jù)。在運(yùn)轉(zhuǎn)期間，定期備份數(shù)據(jù)庫，并當(dāng)數(shù)據(jù)庫損壞或受到影響時(shí)恢復(fù)數(shù)據(jù)庫。1.6 數(shù)據(jù)庫維護(hù) 數(shù)據(jù)庫在數(shù)據(jù)庫維護(hù)期間逐漸發(fā)展。在這一步，為了滿足變化的業(yè)務(wù)條件，為了改正數(shù)據(jù)庫設(shè)計(jì)的錯(cuò)誤，或數(shù)據(jù)庫應(yīng)用的處理速度而增加、刪除或改變數(shù)據(jù)庫的結(jié)構(gòu)特征。當(dāng)一個(gè)程序或計(jì)

10、算機(jī)發(fā)生故障而使數(shù)據(jù)庫受到影響或損壞時(shí)也可能應(yīng)該重建數(shù)據(jù)庫。這一步通常是數(shù)據(jù)庫開發(fā)過程中最長的一步，因?yàn)樗掷m(xù)數(shù)據(jù)庫及相關(guān)應(yīng)用的整個(gè)生命周期，每次數(shù)據(jù)庫的發(fā)展都可看作一個(gè)簡略的數(shù)據(jù)庫開發(fā)過程，其中會出現(xiàn)概念數(shù)據(jù)建模、邏輯和物理數(shù)據(jù)庫設(shè)計(jì)以及數(shù)據(jù)庫實(shí)現(xiàn)以處理提出的變化。二. 信息系統(tǒng)開發(fā)的其他方法 系統(tǒng)開發(fā)生命周期法或其稍作變化的變體經(jīng)常用于指導(dǎo)信息系統(tǒng)和數(shù)據(jù)庫的開發(fā)。信息系統(tǒng)生命周期是一種方法學(xué)，它是高度結(jié)構(gòu)化的方法，它包括許多檢查和權(quán)衡以確保每一步產(chǎn)生精確的結(jié)果，而且新的或替代的信息系統(tǒng)與它必須通信的或數(shù)據(jù)定義需要一致的現(xiàn)存系統(tǒng)保持一致。系統(tǒng)開發(fā)生命周期法經(jīng)常由于產(chǎn)生一個(gè)工作系統(tǒng)需要很長的時(shí)

11、間而受到批評，因?yàn)楣ぷ飨到y(tǒng)僅僅在整個(gè)過程結(jié)束時(shí)才產(chǎn)生。現(xiàn)在組織越來越多的使用快速應(yīng)用開發(fā)法，它是一個(gè)包含分析、設(shè)計(jì)和實(shí)現(xiàn)步驟的快速重復(fù)的迭代過程，直到匯聚到用戶所需的系統(tǒng)為止?？焖賾?yīng)用開發(fā)法在所需的數(shù)據(jù)庫已經(jīng)存在、增強(qiáng)系統(tǒng)主要是為了檢索數(shù)據(jù)的應(yīng)用中適用，而不適用于那些生成和修改數(shù)據(jù)庫的應(yīng)用。 使用最廣泛的快速應(yīng)用開發(fā)法之一是原型法。原型法是一個(gè)系統(tǒng)開發(fā)的迭代過程，通過分析員和用戶的緊密配合，持續(xù)地修改系統(tǒng)而最終將所有需求轉(zhuǎn)換成一個(gè)工作系統(tǒng)。在此圖中我們包含了注釋，概略地描述了每個(gè)原型法階段的數(shù)據(jù)庫開發(fā)活動。一般來說，當(dāng)信息系統(tǒng)的問題被確定時(shí)，僅僅粗略地嘗試概念數(shù)據(jù)建模。在開發(fā)最初的原型時(shí)，設(shè)計(jì)

12、用戶想要的顯示和報(bào)表，同時(shí)理解任何新的數(shù)據(jù)庫需求并定義一個(gè)用語原型的數(shù)據(jù)庫。這通常是一個(gè)新的數(shù)據(jù)庫，它復(fù)制現(xiàn)存系統(tǒng)的一部分，還可能增加了一些新的內(nèi)容。當(dāng)需要新的內(nèi)容時(shí)，這些內(nèi)容通常來自外部數(shù)據(jù)源，如市場研究數(shù)據(jù)、一般的經(jīng)濟(jì)指標(biāo)或行業(yè)標(biāo)準(zhǔn)。 當(dāng)產(chǎn)生原型新的版本時(shí)重復(fù)數(shù)據(jù)庫的實(shí)現(xiàn)和維護(hù)活動。通常僅進(jìn)行最低限度的安全性和完整性控制，因?yàn)榇藭r(shí)的重點(diǎn)是盡可能快地產(chǎn)生可以使用的原型版本。而且文檔管理也延遲到項(xiàng)目的最后，在交付使用時(shí)才進(jìn)行用戶培訓(xùn)。最后，一旦構(gòu)建了一個(gè)可接受的原型，開發(fā)者和用戶將決定最后的原型和數(shù)據(jù)庫是否能交付使用。如果系統(tǒng)（包括數(shù)據(jù)庫）效率很低，那么系統(tǒng)和數(shù)據(jù)庫將被重新編程和重新組織以達(dá)到

13、期望的性能。隨著可視化編程工具（如visual basic、java、visual c+和第四代語言）越來越流行，利用可視化編程工具可以很方便地修改用戶與系統(tǒng)間的界面，原型法正成為可供選擇的系統(tǒng)開發(fā)方法。使用原型法改變用戶報(bào)表和顯示的內(nèi)容和布局是相當(dāng)容易的。在這個(gè)過程中，新的數(shù)據(jù)庫需求被確定，因此被發(fā)展中的應(yīng)用使用的現(xiàn)存的數(shù)據(jù)庫應(yīng)該進(jìn)行修改。甚至有可能為一個(gè)需要新的數(shù)據(jù)庫的系統(tǒng)使用原型法，在這種情況下，當(dāng)系統(tǒng)需求在迭代的開發(fā)過程中不斷變化時(shí)需要獲取樣本數(shù)據(jù)以建造或重建數(shù)據(jù)庫原型。外文原文database development processbased on information engin

14、eering information systems planning database is a source of development projects. these new database development projects is usually in order to meet the strategic needs of organizations, such as improving customer support, improve product and inventory management, or a more accurate sales forecast.

15、 however, many more database development project is the bottom-up approach emerging, such as information system user needs specific information to complete their work, thus beginning a project request, and as other information systems experts found that organizations need to improve data management

16、and begin new projects. bottom-up even in the circumstances, to set up an enterprise data model is also necessary to understand the existing database can provide the necessary data, otherwise, the new database, data entities and attributes can be added to the current data resources to the organizati

17、on.both the strategic needs or operational information needs of each database development projects normally concentrated in a database. some projects only concentrated in the database definition, design and implementation of a database, as a follow-up to the basis of the development of information s

18、ystems. however, in most cases, the database and associated information processing function as a complete information systems development project was part of the development. one. system development life cycleguide management information system development projects is the traditional process of syst

19、em development life cycle (sdlc). system development life cycle is an organization of the database designers and programmers information system composed of the panel of experts detailed description, development, maintenance and replacement of the entire information system steps. this process is beca

20、use waterfall than for every step into the adjacent the next step, that is, the information system is a specification developed by a piece of land, every piece of the output is under an input. however shown in the figure, these steps are not purely linear, each of the steps overlap in time (and thus

21、 can manage parallel steps), but when the need to reconsider previous decisions, but also to roll back some steps ahead. (and therefore water can be put back in the waterfall!) the system development life cycle including each stage and database development-related activities, therefore, the question

22、 of database management systems throughout the entire development process. in figure 5 we repeat of the system development life cycle stage of the seven, and outlines the common database at each stage of development activities. please note that the systems development life cycle stages and database

23、development steps exists between the relationship between the concept of modeling data in both systems development life cycle stages between.1.1 enterprise modeling database development process from the enterprise modeling (system development life cycle stage of the project feasibility studies, and

24、to choose a part)organizations set the scope and general database content. enterprise modeling in information systems planning and other activities, these activities determine which part of information systems need to change and strengthen the entire organization and outlines the scope of data. in t

25、his step, check the current database and information systems, development of the project as the main areas of the nature of the business, with a very general description of each term in the development of information systems when needed data. each item only when it achieved the expected goals of org

26、anizations can be when the next step.1.2 conceptual data modeling one has already begun on the information system project, the concept of data modeling phase of the information systems needs of all the data. it is divided into two stages. first, it began the project in the planning stage. at the sam

27、e time outlining the establishment of other documents to the existing database without considering the circumstances specific development projects in the scope of the required data. this category only includes high-level data (entities), and main contact. then in the system development life-cycle an

28、alysis stage must have a management information system set the entire organization details of the data model definition of all data attributes, listing all data types that all data inter-entity business linkages, defining description of the full data integrity rules. in the analysis phase, but also

29、the concept of inspection data model (also called the concept behind the model) and the goal of information systems used to explain other aspects of the model of consistency categories, such as processing steps, rules and data processing time of timing. however, even if the concept is such detailed

30、data model is only preliminary, because follow-up information system life cycle activities in the design of services, statements, display and inquiries may find that missing element or mistakes. therefore, the concept of data often said that modeling is a top-down manner, its areas of operation from

31、 the general understanding of the driver, rather than the specific information processing activities by the driver. 1.3 logical database design logical database design from two perspectives database development. first, the concept of data model transform into relational database theory based on the

32、criteria that means - between. then, as the design of information systems, every computer procedures (including procedures for the input and output format), database support services, statements, and inquiries revealed that a detailed examination. in this so-called bottom-up analysis, accurate verif

33、ication of the need to maintain the database and the data in each affairs, statements and so on the needs of those in the nature of the data. for each separate statements, services, and so on the analysis must take into account a specific, limited but complete database view. when statements, service

34、s, and other analysis might be necessary to change the concept of data model. especially in large-scale projects, the different analytical systems development staff and the team can work independently in different procedures or in a centralized, the details of their work until all the logic design s

35、tage may be displayed. in these circumstances, logic database design stage must be the original concept of data model and user view these independent or merged into a comprehensive design. in logic design information systems also identify additional information processing needs of these new demands

36、at this time must be integrated into the logic of earlier identified in the database design.logical database design is based on the final step for the formation of good data specifications and determine the rules, the combination, the data after consultation specifications or converted into basic at

37、omic element. most of todays database, these rules from the relational database theory and the process known as standardization, #. this step is the result of management of these data have not cited any database management system for a complete description of the database map. logical database desig

38、n completed, we began to identify in detail the logic of the computer program and maintenance, the report contents of the database for inquiries. 1.4 physical database design and definitionphysical database design and definition phase decisions computer memory (usually disk) database in the organiza

39、tion, definition of according to the library management system for physical structure, the procedures outlined processing services, produce the desired management information and decision support statements. the objective of this stage is to design an effective and safe management of all data-proces

40、sing database, the physical database design to closely integrate the information systems of other physical aspects of the design, including procedures, computer hardware, operating systems and data communications networks. 1.5 database implementation the database prepared by the realization stage, t

41、esting and installation procedures for handling databases. designers can use the standard programming language (such as cobol, c or visual basic), the dedicated database processing languages (such as sql), or the process of the non-exclusive language programming in order to produce a statement of th

42、e fixed format, the result will be displayed, and may also include charts. in achieving stage, but also the completion of all the database files, training users for information systems (database) user setup program. the final step is to use existing sources of information (documents legacy applicati

43、ons and databases and now needs new data) loading data. loading data is often the first step in data from existing files and databases to an intermediate format (such as binary or text files) and then to turn intermediate loading data to a new database. finally, running databases and related applica

44、tions for the actual user maintenance and retrieval of data. in operation, the regular backup database and the database when damaged or affected resume database.1.6 database maintenance during the database in the progressive development of database maintenance. in this step, in order to meet changin

45、g business conditions, in order to correct the erroneous database design, database applications or processing speed increase, delete or change the structure of the database. when a procedure or failure of the computer database affect or damage the database may also be reconstruction. this step usual

46、ly is the longest in the database development process step, as it continued to databases and related applications throughout the life cycle, the development of each database can be seen as a brief database development process and data modeling concepts arise, logical and physical database design and

47、 database to achieve dealing with the changes. two. information system developed by other means system development life cycle minor changes in law or its variant of the often used to guide information systems and database development. information system is a life-cycle methodology, it is highly stru

48、ctured approach, which includes many checks and balances to ensure that every step of produce accurate results, and new or alternative information system and it must communications or data definitions consistent existing system needs consistency. system development life cycle because of the regular

49、need to have a working system for a long time been criticized because only work in the system until the end of the whole process generated. more and more organizations now use rapid application development method, it is a includes analysis, design and implementation of steps to repeat the rapid iter

50、ative process until convergence to users the system so far. rapid application development act required the database has been in existence, and enhance system is mainly to the application of data retrieval application, but not to those who generate and modify database applications. the most widely us

51、ed method of rapid application development is one of the prototype. the prototype system is a method of iterative development process, analysts and users through close co-operation, continuing to revise the system will eventually convert all the needs of a working system. in this diagram we contains

52、 notes, briefly describes each stage of the prototype of the database development activities. normally, when information systems problems were identified, tried only a rough concept of data modeling. in the development of the initial prototype, the design of the user wants to display and statements, and that any new database needs and define a term prototype database. this is usually a new database, copy the part of the