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Intro to GIS | Summer 2012 Attribute Tables – Part 1

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

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  1. Intro to GIS | Summer 2012 Attribute Tables – Part 1

  2. DATABASES

  3. 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

  4. 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

  5. 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

  6. 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”)

  7. Which attribute field is the Attribute Key in this case?

  8. 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)

  9. GEOGRAPHIC (SPATIAL) DATABASES

  10. What is a Geographic (Spatial) Database? • Contains one or more tables with a geographic component (a “shape” attribute) • Common example: an ESRI Geodatabase

  11. Features can be: Constrained (domains) Validated by rules Modeled with complex behavior ESRI Geodatabase Features have: • Shapes • Attributes • Spatial Reference • Relationships

  12. ESRI Geodatabase

  13. 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

  14. “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

  15. Setting the Default Geodatabase - ArcMap

  16. Change location of Default Geodatabase

  17. Setting the Default Geodatabase – ArcCatalog

  18. QUERYING GIS DATA

  19. 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

  20. 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

  21. 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?

  22. “Add XY Data” tool

  23. Bakery list – Excel file

  24. New Point Layer for Bakery Locations

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