1. Introduction: A database is an organized set of data stored in a computer that can be search automatically.
A database is a self describing collection of integrated records. It is self describing because it contains as part of itself a directory or dictionary of its context.
It is a collection of records or a file or a collection of files brought together as a single file commonly accessible by a given set of programme.
According to John Convey, databases are a collection of records in machine readable form that are made available for searching from remote computer terminals.
A database is an organized, integrated and often inter- related collection of computer based data, records, files or information.
A random assortment of data cannot be referred to a database. Databases may be stored on magnetic tape; optical media such as CD- ROM, DVD ROM, and Hard Disk etc. can be accessed either locally or remotely.
2. Characteristic of Database: The characteristic of a database are as follows
a) It is an organized, integrated collection of data.
b) It can be referred to by all relevant application with relative case and number. So duplication of data can be avoided.
c) It is a model of natural relationship of the data in the read- world environment.
d) Database enhances data independence by permitting application programme to be incentive to changes in the database.
e) Databases provide facilities for centralized control of accessing and security control functions.
The database approach can be employed wherever storage and manipulation of data are required. It is most useful when relationships between data are numerous and complex and information requirements are subject to change. Common examples of databases is: A student database containing enrolment data for all persons currently attending classes.
3. Types of database: Databases are of the following types:
a) Bibliographic: In bibliographic databases the data stored comprises input of bibliographical details of a document for identification, storage and retrieval purposes. The bibliographic details to a document may include titles, authors, journal names, volume, issues, place of publications, publisher, year of publication, ISBN/ISSN number, classification number, book number, location keyword, abstract etc.
A bibliographical databases may be a library catalogue or a database of theses, dissertation, research papers published in technical journals, conferences etc.
Bibliographical databases can be divided into two categories:
i) Internal database and associated services: The internal bibliographic databases are those created by libraries and information centres of their published holdings such as books, serial, articles in periodicals, proceedings in conferences, theses etc.
ii) External database and associated services: External bibliographic databases comprise online catalogues such as SCISEARCH. The machine readable counterparts of Science Citation Index, Current Content, the publication of the Institute for Scientific Information, USA, National Union Catalogues of Scientific Serials in India (NISCAIR) etc.
b) Numerical Databases: It contains numeric or statistical or survey type data of information to give answer of numeric queries.
c) Full Text Database: Full text databases contain the full text of a publication, i. e. provide relevant information directly. E.g.: Harvard Business Review (HBR); The New York Times via Naxis
d) Factual Database: Factual database contains directory type data
e) Research in Progress Database: It contains description of research in progress.
Many of the world databases are now made accessible to the users by vendors (computer based agencies that arrange access to various world databases for a fee). Such vendors include DIALOG, SDC etc.
4. Evaluation of Database: The evaluation of a database includes the following-
i) Scope: The bibliographical database should include full bibliographical information such as ISBN/ISSN number, author, title etc.
ii) Indexing System: Which method is used in indexing the database is a prime factor to be considered in evaluation. It should also include the indexing is done by manual or by using automatic method.
iii) Searching facilities: The database should have multiple accesses using various keywords or access point. It should also support Boolean operators.
iv) Vendors Support: Whether the vendor of the database has provide rules, regulation and guidance for using the database or not.