【正文】 管理系統(tǒng)被控制，所有應(yīng)用都利用一個特殊數(shù)據(jù)項來存取被存放在唯一一個地方的相同的數(shù)據(jù)項。數(shù)據(jù)項的一個單獨(dú)的更新，在所有方面都得到更新。用過數(shù)據(jù)庫管理系統(tǒng)的集成要求數(shù)據(jù)庫的一個中央集權(quán)。數(shù)據(jù)可能被放在一個中央計算機(jī)里或者被分散在幾個計算機(jī)之中；最重要的 要求是擁有一個組織功能來執(zhí)行控制。 對接受人來說只接收原始數(shù)據(jù)或者甚至是總結(jié)的數(shù)據(jù)都是不夠的。數(shù)據(jù)通常需要被處理和被呈現(xiàn)出來，以結(jié)果指向所作的決定的方式。這樣，數(shù)據(jù)項的處理建立于決策模型。例如，一項投資決定相對于新的資本支出也許根據(jù)一項政府支出決定模型被處理。 決定模型可以在決策過程中被用來支持不同的階段。 “智能 ”模型可以用來尋找問題或者機(jī)會。模型可以被用來辨認(rèn)和分析可能的解決方案。挑選模型，例如最優(yōu)化模型可以被用來發(fā)現(xiàn)最想要的解決方案。 換句話說，面對各種各樣的決策情況需要多種的方法。下面是一些例子和可能 被包含在一個管理信息系統(tǒng)中用來幫助分析和支持決策的模型的類型；一個全面的信息系統(tǒng)，決策者擁有一套有用的普通模型，可以應(yīng)用于許多分析和決定的情況，還有一套非常特殊的模型應(yīng)用于特別的決定。相似的模型可以用來計劃和控制。選擇的模型是管理信息系統(tǒng)的模型基礎(chǔ)。 在不同的情況下，當(dāng)管理人員可以使用交互式的對話建立一個計劃或者通過幾個決定選擇重復(fù)敘述，模型一般是最有效的 。 DATABASE MANAGEMENT SYSTEMS（ DBMS） AND MANAGEMENT INFORMATION SYSTEM（ MIS） You know that a database is a collection of logically related data elements that may be structured in various ways to meet the multiple processing and retrieval needs of organizations and individuals． There? s nothing new about databases—early ones[1] were chiseled in stone， penned on scrolls， and written on index cards． But now databases are monly recorded on magizable media， and puter programs are required to perform the necessary storage and retrieval operations． You?ll see in the following pages that plex data relationships and linkages may be found in all but the simplest databases[2]． The system software package that handles the difficult tasks associated with creating， accessing， and maintaining database records is called a database management system（ DBMS）． The programs in a DBMS package establish an interface between the database itself and the users of the database．（ These users may be applications programmers， managers and others with information needs， and various OS programs．） A DBMS can organize， process， and present selected data elements from the database． This capability enables decision makers to search， probe， and query database contents in order to extract answers to nonrecurring and unplanned questions that aren?t available in regular reports[3]． These questions might initially be vague and / or poorly defined， but people can“browse”through the database until they have the needed information． In short， the DBMS will“manage”the stored data items and assemble the needed items from the mon database in response to the queries of those who aren?t programmers． In a fileoriented system， users needing special information may municate their needs to a programmer， who， when time permits， will write one or more programs to extract the data and prepare the information[4]． The availability of a DBMS， however， offers users a much faster alternative munications path（ see Fig. 71）． If the DBMS provides a way to interactively and update the database, as well as interrogate it capability allows for managing personal dataAces however, it does not automatically leave an audit trail of actions and does not provide the kinds of controla necessary in a multiuser organization. Thesecontrols are only available when a set of application programs are customized for each data entry and updating function. Software for personal puters which perform me of the DBMS functions have been very popular arsenal puters were intended for use by individuals for personal information storage and process These machines have also been used extensively small enterprises, professionals like doctors, acrylics, engineers, lawyers and so on ． By the nature of. intended usage, database systems on these machines except from several of the requirements of full doge database systems． Since data sharing is not：Tended, concurrent operations even less so, the) fewer can be less plex. Security and integrity7aintenance are deemphasized or absent. As data) limes will be small, performance efficiency Is also important. In fact, the only aspect of a database system that is Important 39。is data Independence. , as stated earlier. Means that applicant programs and user queries need not recognizant?physical organization of data on secondary storage. The importance of this aspect, particularly for the personal puter user, is that this greatly simplifies database usage. The user can store, access and manipulate data at a high level (close to the application) and be totally shielded fr