DATABASE MANAGEMENT

Database Management

Database Management

Introduction

Developed in the 1960s by computer scientists who required an efficient storage and access mechanism for large data sets, database management systems (DBMS) have become a core component of present-day information systems. Database technology drives billions of transactions each day, from the grocery store purchases to Web searches. (Codd, 2009)

The technology is also critical to research applications. DBMS facilitate efficient, scalable, secure storage of data and include query and manipulation tools that can be controlled via the standard structured query language (SQL). Properly applied database design techniques produce databases that eliminate data redundancy and provide for efficient queries across multiple tables. In geography, DBMS are used in multiple ways but are best known as a key component of geographic information systems (GIS), where they enable the storage and manipulation of attribute data associated with spatial features. Certain GIS data formats contain file-based attribute data, while others store attributes in a database table. Spatial databases are specially constructed to hold spatial features and their attributes and to provide functions for performing spatial analysis operations within a database. (Rigaux, 2010)

Definition and History of Database Models

A database is simply a structured collection of related data. While the term database could refer to any collection of data, such as a set of alphabetically sorted recipes on index cards, it most commonly refers to a set of data stored electronically. A DBMS consists of a database and the associated software constructs that not only maintain interrelationships among the stored data but also provide methods for data insertion, manipulation, and extraction. (Codd, 2009)

A database model describes the structure of a database. Several DBMS implementations emerged in the 1960s that employed either the network model or the hierarchical model, which together represented the first generation of database models. Although these early models differed in implementation, they both represented data as records with links (from one record to another) that described relationships among the records. This approach provided limited search capabilities and was inefficient when dealing with databases containing empty records. In 1970 Edgar Codd described the relational model, which represented a groundbreaking approach to database modeling that solved many limitations of the linked-list approach of the first-generation models. Codd's work eventually guided the development of the relational DBMS, which remains the most widely implemented DBMS standard today. In later years, the object-relational model emerged, which supported the object-oriented programming concepts of objects, classes, and inheritance within the database. Many outstanding DBMS support both relational and object-relational models. (Zeiler, 2009)

Relational Database Management Systems

Relational databases offer many advantages over file-based information systems. Although text files are accessible, are easy to read and edit, and can be processed in many ways, they do not scale well when dealing with large data sets, have limited structuring, and may contain redundant data. A relational DBMS can handle enormous data sets and maintain data integrity, eliminate data redundancy, enable user-based security, and provide structured methods for querying and manipulating the data. (Codd, 2009)

Relational Database Structure and Design

A relational database contains a ...