【正文】 plus a set of very specific models for unique decisions. Similar models are available for planning and control. The set of models is the model base for the MIS. 1 Models are generally most effective when the manager can use interactive dialog to build a plan or to iterate through several decision choices under different conditions. 眾所周知，數(shù)據(jù)庫是邏輯上相關(guān)的數(shù)據(jù)元的匯集。 the results are displayed on the screen in a few second. The puterbased usermachine characteristics of an MIS affect the knowledge requirements of both system developer and system user. “puterbased” means that the designer of a management information system must have a knowledge of puters and of their use in processing. The “usermachine” concept means the system designer should also understand the capabilities of humans as system ponents (as information processors) and the behavior of humans as users of information. Information system applications should not require users to be puter experts. However, users need to be able to specify their information requirements。 manual procedures。 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 anizations 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 anize， 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 anization. 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