Tuesday, September 22, 2015

DBMS used by GIS and relational database model

A DBMS or Database Management System is a set of computer programs for managing an integrated or shared database.

A DBMS provides tools for:
-Data input
-Search
-Retrieval
-Manipulation and output

Arc/Info uses Info and ArcView uses dBase to handle local files
AutoCAD Map uses VISION to manage its database
MGE uses database management tools from Oracle/Informix & provides an interface to other DBMS

The relational database model
A database is a collection of interrelated tables in digital format.
The four types of database design are:
-Flat file
-Hierarchical
-Network and
-Relational

A flat file contains ALL data in a LARGE TABLE
Ex:- Extended feature attribute table or a spreadsheet

A hierarchical database organizes data at many levels and uses only ONE-TO-MANY association between levels

A network database builds connections across tables

Network database design and hierarchical database require that linkages between tables must be known in advance. This requirement makes the database complicated and inflexible

Compared to other database designs, a relational database is simple and flexible

Each table in the database can be prepared, maintained and edited separately from other tables

The tables can remain separate until a query or analysis requires attribute data from different tables to be linked together
Since the need for linking tables is temporary, a relational database is efficient for both data management and data processing.