WHAT IS A DATABASE?
When you use an automated teller machine to withdraw money from your bank account, you are using a database. When a travel agent makes an airline reservation for you, she is using a database. When a telephone operator gives you a phone number, he is using a database. Any significant collections of information stored on computers are virtually always organized as databases. Databases dealing with published information usually found in libraries, such as books, articles and other types of documents, are commonly called bibliographic databases. Until recently, bibliographic databases have been primarily access tools. Access tools--such as catalogs and indexes--do not give you the actual book, article or other material with the full information you'll need for your research; they give you enough information to find that material. As you'll learn later in this chapter, it is now more and more common to find databases that go beyond just access tools and include the full text or other information from articles, books or other documents. Understanding the elements of databases and how they work is a key to accessing information in the information age.
Earlier we defined a database simply as a collection of
information organized in a systematic form so that specific pieces of
the information can be easily accessed. If we take the books in a
library and list the title, author and subject(s) of each book, we
have a collection of information that can be organized as a database.
The trick is to use a form of organization that can make it easy to
find all of the books on a specific subject or by a particular
author.
All databases are organized by two basic elements: records and fields.
Records are the units of information that can be retrieved. In our library example, all of the information describing each book is a record. In a perioidcal database, a record is all of the information for one article (the citation, abstract and full-text, if available).
Fields are the different parts of a record by which the record is retrievable. The fields in our example are title, author and subject. Let's look at how records and fields are arranged in a very limited library database.
(FIELD 1) AUTHOR |
(FIELD 2) TITLE |
(FIELD 3) SUBJECT(S) |
|
RECORD 1 |
HYMAN, RICHARD |
INFORMATION ACCESS |
ONLINE BIBLIOGRAPHIC SEARCHING; BIBLIOGRAPHICAL SERVICES; CATALOGING--HISTORY |
RECORD 2 |
MOSCO, VINCENT |
THE POLITICAL ECONOMY OF INFORMATION |
COMMUNICATION; INFORMATION SCIENCE--ECONOMIC ASPECTS; MASS MEDIA |
RECORD 3 |
SAXBY, STEPHEN |
THE AGE OF INFORMATION |
COMPUTERS AND CIVILIZATION; INFORMATION TECHNOLOGY--SOCIAL ASPECTS |
RECORD 4 |
TECHRANIAN, MAJID |
TECHNOLOGIES OF POWER |
INFORMATION TECHNOLOGY--SOCIAL ASPECTS; DEMOCRACY |
RECORD 5 |
TUCKER, FRANK |
THE FRONTIER SPIRIT AND PROGRESS |
CIVILIZATION, MODERN--1950- ; MASS MEDIA; PROGRESS |
RECORD 6 |
WOODWARD, KATHLEEN |
THE MYTHS OF INFORMATION |
TECHNOLOGY AND CIVILIZATION; INFORMATION THEORY; MASS MEDIA |
You can see that in this simple database, each line of information
is a record and each column of information represents a field. When
information is organized in this way in a computerized database, the
process of retrieving information can be automated.
Let's see what actually happens when we try to access information in this computerized database. There are two basic methods commonly used to retrieve records from a database. The first method involves looking through an alphabetical list of all of the words in a particular field. In database terminology, such a list is called an "index." In our simplified database, the subject "index" would look like this:
BIBLIOGRAPHICAL SERVICES
CATALOGING--HISTORY
CIVILIZATION, MODERN--1950-
COMMUNICATION
COMPUTERS AND CIVILIZATION
DEMOCRACY
INFORMATION SCIENCE--ECONOMIC ASPECTS
INFORMATION TECHNOLOGY--SOCIAL ASPECTS
INFORMATION THEORY
MASS MEDIA
ONLINE BIBLIOGRAPHIC SEARCHING
PROGRESS
TECHNOLOGY AND CIVILIZATION
In order to find all of the records on a specific subject, such as "mass media", we could simply look through the subject index to see if that subject is listed. If we find a subject in the index, we know that there are records on this subject in the database and we can simply select that subject in order to view all of the records on the subject. If we select MASS MEDIA from this index, the database program displays the following records:
(FIELD 1) AUTHOR |
(FIELD 2) TITLE |
(FIELD 3) SUBJECT(S) |
|
RECORD 1 |
MOSCO, VINCENT |
THE POLITICAL ECONOMY OF INFORMATION |
COMMUNICATION; INFORMATION SCIENCE--ECONOMIC ASPECTS; MASS MEDIA |
RECORD 2 |
TUCKER, FRANK |
THE FRONTIER SPIRIT AND PROGRESS |
CIVILIZATION, MODERN--1950- ; MASS MEDIA; PROGRESS |
RECORD 3 |
WOODWARD, KATHLEEN |
THE MYTHS OF INFORMATION |
TECHNOLOGY AND CIVILIZATION; INFORMATION THEORY; MASS MEDIA |
This process of looking through an index to find the right word(s)
to retrieve specific records is commonly called "browsing" an index.
Browsing an index is especially useful when you are not sure what
word(s) to use for a search.
The second method of accessing records-- commonly called "keyword searching"-- does not display an index. A "keyword search" simply looks for all of the records that contain the given word or words-- sometimes called "keyword(s)" or "search term(s)". A "keyword search" may or may not be limited to a specified field or group of fields. If we do a "keyword search" for "information" in all of the fields in our database, the computer looks for any appearance of the word, "information", anywhere in any record. All of the records containing "information" are then copied into a new list, or "set", of records. The resulting set is shown below:
(FIELD 1) AUTHOR |
(FIELD 2) TITLE |
(FIELD 3) SUBJECT(S) |
|
RECORD 1 |
HYMAN, RICHARD |
INFORMATION ACCESS |
ONLINE BIBLIOGRAPHIC SEARCHING; BIBLIOGRAPHICAL SERVICES; CATALOGING--HISTORY |
RECORD 2 |
MOSCO, VINCENT |
THE POLITICAL ECONOMY OF INFORMATION |
COMMUNICATION; INFORMATION SCIENCE--ECONOMIC ASPECTS; MASS MEDIA |
RECORD 3 |
SAXBY, STEPHEN |
THE AGE OF INFORMATION |
COMPUTERS AND CIVILIZATION; INFORMATION TECHNOLOGY--SOCIAL ASPECTS |
RECORD 4 |
TECHRANIAN, MAJID |
TECHNOLOGIES OF POWER |
INFORMATION TECHNOLOGY--SOCIAL ASPECTS; DEMOCRACY |
RECORD 5 |
WOODWARD, KATHLEEN |
THE MYTHS OF INFORMATION |
TECHNOLOGY AND CIVILIZATION; INFORMATION THEORY; MASS MEDIA |
This illustrates the most basic process of "database searching"-- that is, looking up information using a computerized database. Notice that it is essentially a system of matching words. The searcher must come up with the right word (or combination of words) that exactly match the same word(s) within the records that are needed. The "browse" method uses an index in a database to help identify the desired search term in a specific field. The "keyword search" method looks directly for records containing the given search terms without displaying an index and without necessarily limiting the search to a specific field.
It is important to realize that computers do not "understand" anything you type into them. They simply do very quick matching of the characters you enter. You can't expect the computer to automatically understand exactly what you are looking for and then give you just the information you need. In order to be effective in accessing information from computers, you need to keep in mind the basic way databases function. It is very important to 1) first choose the best word(s) to use for a search and 2) then analyze the data that the computer provides in order to refine your search.
Database Types
Access Tools
Our database example is actually a reduced and simplified version
of one common type of library database-- a computerized catalog,
usually called an online catalog. A catalog is also a type of access
tool. Other access tools include periodical indexes and abstracts. An
access tool is a computerized database or print source that helps you
find the book, article, document, audiovisual or other material that
you need. It does not include the actual material you'll read or
view, but it gives you the information you'll need to access that
material. After you use an access tool, you must then retrieve the
actual book, article or other material by either finding it in a
library (or bookstore) or ordering it to be sent to you--typically
through a library interlibrary loan service or through a commercial
document delivery service. (See for more information on interlibrary
loan and document delivery services.)
Online Catalogs
Online catalogs generally list all of the books in a particular library or group of libraries. They are computerized versions of card catalogs, which have traditionally been used for the same purpose. In our simple book database, the information in each record-- just author, title and subject for each book-- contains quite a bit less information than most actual catalogs. In a typical catalog, each record usually contains not only author, title and subject information, but also other information such as the publisher, place of publication, publication date and the book's call number. The call number is the set of letters and numbers on the spine of the book that indicate where the book is located on the library shelves. By including the call number, the online catalog gives you the information you need to access the book--to find the book on the shelf. When a record consists of this type of basic information about a book or article, it is commonly called a citation. Databases made up exclusively of citations are generally the simplest types of bibliographic databases since each citation includes only the most essential information about a book or other document. The following is an example of a citation from the University of California online catalog, called Melvyl:
Author: Bender, David R. Title: National information policies : strategies for the future /David R. Bender, Sarah T. Kadec, Sandy I. Morton. Washington, DC : Special Libraries Association, c1991.Description: iv, 62 p. ; 28 cm.Series: SLA occasional papers series ; no. 2. Notes: Includes bibliographical references (p. 48-58).
Subjects: Information services and state -- United States. Information science -- Government policy -- United States.
Other entries: Kadec, Sarah T. Morton-Schwalb, Sandy I.
Call numbers: UCB LibSchLib Z678.2 .B45 1991
Periodical databases
Indexes to articles in magazines, newspapers or journals are another common access tool made up primarily of citations. Many of these indexes are available in computerized form. Since magazines, newspapers and journals are all referred to in libraries as "periodicals" (publications that are published "periodically"), databases that list articles from these types of publications are commonly referred to as periodical indexes. (Be sure not to confuse the different uses of the word "index." "Index" is used here to describe a general type of database as distinguished from the use of "index" when referring to the part of a database described previously, i.e., an alphabetical list of all of the words in a particular field.) A typical citation in an index to magazine articles consists of the author, title and page numbers of the article and the title, date and volume number of the magazine. Occasionally, if the title does not identify the content of the article, a brief amount of description will be added (usually in parentheses after the title), as in the following example of a citation from Academic Index database (published by Information Access):
Bewildering the herd. (interview with Noam Chomsky on the mass media industry) by Rick Szykowny il v50 The Humanist Nov-Dec '90 p8(10) 57E3601
In addition to the basic citation data for each article, most periodical databases include abstracts--short summaries of the articles. Abstracts are generally from a couple of sentences to a few paragraphs in length and are included in each record following the basic citation. In databases that include abstracts, the text of the abstract usually makes up a separate field. When searching for articles on a particular subject in an abstract database, a researcher can search for a particular keyword or words, not only in the subject or title fields, but anywhere in the entire abstract. Although periodical databases are the most common type of database that includes abstracts, other types of databases may also include abstracts. One well-known abstract database that is not a periodical database is Dissertation Abstracts, which includes summaries of doctoral dissertations and masters theses. The following example is a record from Periodical Abstracts database (published by UMI):
92239317Title: Why the Old Media's Losing Ground
Authors: Alter, Jonathan
Journal: Newsweek Vol: 119 Iss: 23 Date: Jun 8, 1992 pp: 28
Jrnl Code: GNEW ISSN: 0028-9604 Jrnl Group: News
Abstract: The mainstream media seems to have lost control of the 1992 presidential election and is splitting into two parts: Old Media, which consists of network TV, big newspapers and magazines, public TV and elite journalists, and New Media, which includes the less elitist and more democratic CNN, C-Span, infotainment talk shows, computer bulletin boards and satellite hookups. PhotographSubjects: Presidential elections; Mass media
Type: Commentary
Length: Medium (10-30 col inches)
Access Tools vs. Full-Text Databases
Catalogs and index and abstract databases are considered access
tools since they just provide citation or summary information--but
not the full text of the document. As computer technology has rapidly
increased in speed and storage capacity over the last decade, it has
become common to find databases that include the full text of
documents as part of the database itself. Databases that include the
full documents are called full-text databases.
Full-Text Databases
In recent years, full-text databases have become the most popular
type of database. As the name implies, records in full-text databases
include the complete text of the articles or other types of documents
included in the database. The most common examples of full-text
databases are computerized encyclopedias and newspaper databases.
Many general periodical databases now include the full-text of
growing numbers of the periodicals in the databases. More scholarly
and academic journals have been slower to be produced in full-text
format but they are also becoming increasingly available online. One
advantage of most full-text databases is that all of the words in the
entire text of the articles can be searched to find just those
articles containing specified keywords. The following example is a
relatively short full-text record from the InfoTrac OneFile
periodical database:
|
Blurred Distinctions
The distinctions between different bibliographic database types is not always very precise because it is increasingly common to find databases that include different types of records. Many periodical databases that originally only included citations, now include abstracts in most records and the full-text of articles from a portion of the indexed periodicals.
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last revised:10-19-04 by Eric Brenner, Skyline College, San Bruno,
CA
These materials may be used for educational purposes if you inform and credit the author and cite the source as: LSCI 106 Online Research. All commercial rights are reserved. To contact the author, send comments or suggestions, email: Eric Brenner at brenner@smccd.net