Database Management System

Section I: Managing Data Resources

DATA RESOURCE MANAGEMENT

Data is a vital organizational resource, which needs to be managed like other important business assets.  Most organizations could not survive or succeed without quality data about their internal operations and external environment.  Managers need to practice data resource management - a managerial activity that applies information systems technology like database management and other management tools to the task of managing an organization's data resources to meet the information needs of business users.

FOUNDATION DATA CONCEPTS

A hierarchy of several levels of data has been devised that differentiates between different groupings, or elements, of data.  Data are logically organized into:

·         Character - A character is the most basic logical data element.  It consists of a single alphabetic, numeric, or other symbol.

·         Field - A field consists of a grouping of characters.  A data field represents an attribute (a characteristic or quality) of some entity (object, person, place, or event).

·         Record - Related fields of data are grouped to form a record.  Thus, a record represents a collection of attributes that describe an entity.  Fixed-length records contain a fixed number of fixed-length data fields.  Variable-length records contain a variable number of fields and field lengths.

·         File - A group of related records is known as a data file, or table.  Files are frequently classified by the application for which they are primarily used, such as a payroll file or an inventory file, or the type of data they contain, such as a document file or a graphical image file.  Files are also classified by their permanence, for example, a master file versus a transaction file.  A transaction file would contain records of all transactions occurring during a period, whereas a master file contains all the permanent records.  A history file is an obsolete transaction or master file retained for backup purposes or for long-term historical storage called archival storage.

·         Database - A database is an integrated collection of logically related records or objects.  A database consolidates records previously stored in separate files into a common pool of data records that provides data for many applications.  The data stored in a database is independent of the application programs using it and of the type of secondary storage devices on which it is stored.

TYPES OF DATABASES

Continuing developments in information technology and its business applications have resulted in the evolution of several major types of databases. Several major conceptual categories of databases that may be found in computer-using organizations include:

·         Operational Databases - These databases store detailed data needed to support the operations of the entire organization.  They are also called subject area databases (SADB), transaction databases, and production databases.  Examples are customer databases, personnel databases, inventory databases, and other databases containing data generated by business operations.

·         Distributed Databases - Many organizations replicate and distribute copies or parts of databases to network servers at a variety of sites.  These distributed databases can reside on network servers on the World Wide Web, on corporate Intranets or extranets, or on other company networks.  Distributed databases may be copies of operational or analytical databases, hypermedia or discussion databases, or any other type of database.  Replication and distribution of databases is done to improve database performance and security.

·         External Databases - Access to external, privately owned online databases or data banks is available for a fee to end users and organizations from commercial online services, and with or without charge from many sources on the Internet, especially the Web.

·         Hypermedia Databases on the Web:  [Figure  3.6]  - The rapid growth of web sites on the Internet and corporate Intranets and extranets has dramatically increased the use of databases of hypertext and hypermedia documents. A web site stores such information in a hypermedia database consisting of a home page and other hyperlinked pages of multimedia or mixed media (text, sound, etc.).

DATA WAREHOUSES AND DATA MINING

·         Data Warehouses - A data warehouse stores data from current and previous years that has been extracted from the various operational and management databases of an organization.  It becomes a central source of data, which has been screened, edited, standardized, and integrated so it can be used by managers and other end user professionals throughout an organization.  Data warehouses may be subdivided into data marts, which hold specific subsets of data from the warehouse. 

·         Data Mining - A major use of data warehouse databases is data mining.  In data mining, the data in a data warehouse are processed to identify key factors and trends in historical patterns of business activity that can be used to help managers make decisions about strategic changes in business operations to gain competitive advantages in the marketplace.