Database is a body of information made up of related pieces of data organized so that they can be easily manipulated by computer. Databases are defined, accessed (retrieved), and maintained by means of a program called a database management system (DBMS).
Using a programming language called a database query language, or an application program, users define the sort of data they seek. For example, a retail Internet website translates a user’s input into a request for the DBMS. The DBMS then instructs the computer to retrieve data that match the definition. In some systems, users can enter items into databases by filling in forms that represent various fields (categories). If a database is properly organized, the DBMS can support a wide variety of applications that use, and even manipulate, the same data.
Databases are used in many fields, including government, business, and education. Stores use databases to track customers’ purchases and brand preferences. Databases help polling firms organize statistics on public opinion. Many schools use databases to maintain student records. Other bodies of information managed by database programs include expense records, mailing lists, and tax records.
The information in a database is stored in one or more computer files, each consisting of many records. Each record contains pieces of information concerning one item, organized into fields. In a library’s online catalog, for example, the items are books, and the fields include such information as title, author, publisher, and date of publication. To determine whether a library has a copy of a certain book, an individual can select the title field, then type all or part of the book’s title. Or, using the author field, a person can call up a list of all of the library’s books written by a particular author. The records and fields in a database can be thought of as a table with rows of records and columns of fields. Many database displays present data as such tables.
A flat-file database, such as an online catalog, enables a user to call up data from only one file at a time. A relational database can draw data from more than one file. A librarian might use a relational database to search for information on a particular area of study. The database might list individuals or agencies doing research, periodicals that cover the subject area, or books about the subject.
See also Information retrieval; Search engine.
