Intro to GIS | Summer 2012
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Intro to GIS | Summer 2012 Attribute Tables – Part 1. DATABASES. Why do we care about Databases?. Integrated sets of data Focused on a particular area and subject Form the basis of GIS analysis and decision-making

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Intro to gis summer 2012 attribute tables part 1

Intro to GIS | Summer 2012

Attribute Tables – Part 1


Intro to gis summer 2012 attribute tables part 1

DATABASES


Intro to gis summer 2012 attribute tables part 1

Why do we care about Databases?

  • Integrated sets of data

  • Focused on a particular area and subject

  • Form the basis of GIS analysis and decision-making

  • Must be well-structured in order for us to best access the information stored in them


Intro to gis summer 2012 attribute tables part 1

How are Databases Managed?

  • Database Management System (DBMS) = system or software program(s) that enables you to store, modify and extract information from a database


Intro to gis summer 2012 attribute tables part 1

Relational Database (RDBMS)

  • Supports the representation of data as a set of tables that are related to each other

  • Each table = a list of records containing attributes about features

  • Tied together by a “Attribute Key” = an attribute field common to both tables


Intro to gis summer 2012 attribute tables part 1

Table Data Structure

Record: a row in a database; represents one feature (a.k.a. “tuple”)

Attribute: a column in a database; contains attribute values (a.k.a. “field”)


Intro to gis summer 2012 attribute tables part 1

Which attribute field is the Attribute Key in this case?


Intro to gis summer 2012 attribute tables part 1

Object (ODBMS) & Object-Relational (ORDBMS) Databases

  • ODBMS = Supports the representation of data as objects having attributes, methods and behavior

    • e.g. ArcGIS geodatabases

  • Designed to address the weaknesses of RDBMS such as:

    • Geometry and attribute data are stored in separate databases

    • Poor performance for many types of geographic query

  • Geographic extensions to standard RDBMS can provide similar functionality (ORDBMS)


Intro to gis summer 2012 attribute tables part 1

GEOGRAPHIC (SPATIAL) DATABASES


Intro to gis summer 2012 attribute tables part 1

What is a Geographic (Spatial) Database?

  • Contains one or more tables with a geographic component (a “shape” attribute)

  • Common example: an ESRI Geodatabase


Esri geodatabase

Features can be:

Constrained (domains)

Validated by rules

Modeled with complex behavior

ESRI Geodatabase

Features have:

  • Shapes

  • Attributes

  • Spatial Reference

  • Relationships


Intro to gis summer 2012 attribute tables part 1

ESRI Geodatabase


Types of geodatabases

Types of Geodatabases

Personal

  • Single-user

  • Microsoft Access

  • Up to 2 GB storage

    File

  • Single-user

  • File folder structure

  • Up to 1 TB storage

ArcSDE

  • Multi-User, supports versioning

  • Oracle, Microsoft SQL Server, IBM DB2, IBM Informix, PostgreSQL

  • Storage limit based on DBMS type

ESRI Comparison of Geodatabases


Default geodatabase

“Default” Geodatabase

  • A setting in ArcGIS

  • Helps with data management

  • Allows you to:

    • Store all datasets in one convenient location, or

    • Set a database for each project


Setting the default geodatabase arcmap

Setting the Default Geodatabase - ArcMap


Change location of default geodatabase

Change location of Default Geodatabase


Setting the default geodatabase arccatalog

Setting the Default Geodatabase – ArcCatalog


Intro to gis summer 2012 attribute tables part 1

QUERYING GIS DATA


Intro to gis summer 2012 attribute tables part 1

Getting Information from GIS data

  • Query = to question or inquire about a feature(s) shown on a map (and by extension, in a GIS dataset)

  • Output is a selected set of records

  • Two approaches:

    • Attribute queries

    • Spatial queries


Intro to gis summer 2012 attribute tables part 1

Attribute Queries

  • Selects features based on non-spatial information in an attribute table

    • e.g. Which counties in the US have > 100,000 people?

  • “Select By Attributes” tool in ArcMap

  • SQL (structured query language) used to write query


Intro to gis summer 2012 attribute tables part 1

Spatial Queries

  • Selects features based on location or spatial relationship between data layers

    • e.g. Which Oregon counties have an interstate highway passing through them?

  • “Select Layer by Location” tool in ArcMap

    • Target layer = base layer; contains features you want selected

    • Filter layer = comparison layer

  • What kind of spatial relationships are possible between points, lines and polygons?


  • Add xy data tool

    “Add XY Data” tool


    Bakery list excel file

    Bakery list – Excel file


    New point layer for bakery locations

    New Point Layer for Bakery Locations


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