Advantages and Types of Database System

Advantages of a database approach

• reduction in data redundancy
• shared rather than independent databases
• reduces problem of inconsistencies in stored information, e.g. different addresses in different departments for the same customer
• maintenance of data integrity and quality
• data are self-documented or self-descriptive
• information on the meaning or interpretation of the data can be stored in the database, e.g. names of items, metadata
• avoidance of inconsistencies
• data must follow prescribed models, rules, standards
• reduced cost of software development
• many fundamental operations taken care of, however DBMS software can be expensive to install and maintain
• security restrictions
• database includes security tools to control access, particularly for writing

Types of database systems

• several models for databases:
• tabular ("flat file") - data in a single table
• hierarchical
• network
• relational
• the hierarchical, network and relational models all try to deal with the same problem with tabular data:
• inability to deal with more than one type of object, or with relationships between objects
• e.g. database may need to handle information on aircraft, crew, flights and passengers - four types of records with different attributes, but with relationships between them (e.g. "is booked on" between passenger and flight)
• database systems originated in the late 1950s and early 1960s largely by research and development of IBM Corporation
• most developments were responses to needs of business, military, government and educational institutions - complex organizations with complex data and information needs
• trend through time has been increasing separation between the user and the physical representation of the data - increasing "transparency"

• http://www.geog.ubc.ca/courses/klink/gis.notes/ncgia/u43.html#SEC43.2.2