Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available athttp://www.jstor.org/page/info/about/policies/terms.jsp. JSTOR's Terms and Conditions of Use provides, in part, that unless you have obtained prior permission, you may not download an entire issue of a journal or multiple copies of articles, and you may use content in the JSTOR archive only for your personal, non-commercial use. Please contact the publisher regarding any further use of this work. Publisher contactinformation may be obtained at http://www.jstor.org/action/showPublisher?publisherCode=aaas. Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printed page of such transmission. JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digitalarchive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact email@example.com.
American Association for the Advancement of Science is collaborating with JSTOR to digitize, preserve and extend access to Science.
Michael W. Blasgen
Computer systems areincreasingly used to aid in the management of information, and as a result, new kinds of data-oriented software and hardware are needed to enhance the ability of the computer to carry out this task. This article reviews the rapidly evolving field of database systems-computer systems devoted to the management of relatively persistent data. The computer software employed in a database system iscalled a database management system (DBMS). There are more than 15,000 database systems installed in the United States, and these systems are being directly used by hundreds of thousands of people. Indirectly, almost every citizen uses one or more of these systems, since it is not possible today to write a check, use a credit card, make an airline reservation, or pay a bill without causing an actionin a database. Most database systems are oriented toward the modification and retrieval of formatted data-the kind of data associated with the management of inventories, accounts payable and receivable, personnel information, and other administrative applications. Some systems (called information retrieval systems) are oriented toward the search and retrieval (not update) of unformatted text-ascientific abstracts service, for example. There are now approximately 1000 different information retrieval services that can be tapped by subscribers, up from 400 two years ago (1). In addition to these "mundane" database systems, a small but growing number of database systems are employed for more exotic applications such as (i) managing the engineering drawings for a new commercial airliner andusing the drawing information to directly drive numerically controlled machine tools; (ii) storing the three-dimensional structures of organic compounds and their pharmacological properties so that proposed drugs can be rapidly compared with other compounds and their properties more accurately predicted; and (iii) storing and manipulating geographic information
SCIENCE, VOL. 215, 12 FEBRUARY 1982such as maps, digitized photographs, and Landsat images, which then permit image enhancement and pattern recognition in applications such as oil exploration and land use planning. But it is not necessary to appeal to these advanced applications to understand the technical challenges of database systems. It is sufficient to consider a relatively simple example.
A Banking Example To understand...