1、 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 ab
2、out databasesearly ones1 were chiseled in stone，penned on scrolls， and written on index cards But now databases are commonly recorded on magnetizable media， and computer programs are required to perform the necessary storage and retrieval operations Youll see in the following pages that complex data
3、 relationships and linkages may be found in all but the simplest databases2 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 int
4、erface 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 maker
5、s to search， probe， and query database contents in order to extract answers to nonrecurring and unplanned questions that arent available in regular reports3 These questions might initially be vague and / or poorly defined， but people can“browse”through the database until they have the needed informa
6、tion In short， the DBMS will“manage”the stored data items and assemble the needed items from the common database in response to the queries of those who arent programmers In a file-oriented system， users needing special information may communicate their needs to a programmer， who， when time permits，
7、will write one or more programs to extract the data and prepare the information4 The availability of a DBMS， however， offers users a much faster alternative communications path（ see Fig. 7-1） If the DBMS provides a way to interactively and update the database, as well as interrogate it capability al
8、lows for managing personal data-Aces however, it does not automatically leave an audit trail of actions and does not provide the kinds of controla necessary in a multiuser organization. These-controls are only available when a set of application programs are customized for each data entry and updati
9、ng function. Software for personal computers which perform me of the DBMS functions have been very popular arsenal computers were intended for use by individuals for personal information storage and process- These machines have also been used extensively small enterprises, professionals like doctors
10、, 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 complex. Security and inte
11、grity7aintenance are de-emphasized 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 is data Independence. Data-.dependence, as stated earlier. Means that applicant programs and user queries need not re
12、cognizantphysical organization of data on secondary storage. The importance of this aspect, particularly for the personal computer 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 f
13、rom the low level (close to the machine) details of data organization. We will not discuss details of specific PC DBMS software packages here Let us summarize in the following the strengths and weaknesses of personal computer data-base software systems： The most obvious positive factor is the user friendliness of the software. A user with no prior computer background would be able to use the system to store personal and professional data, retrieve and perform relayed processing. The
