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Data Queries. Selecting features in ArcMap. Data queries. Important part of a GIS project Can be a part of your data preparation or final analysis Data Queries (selecting data based on a question or criteria) Attribute Query Spatial Data Query. Attribute Data Query.

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Data queries

Data Queries

Selecting features in ArcMap


Data queries1
Data queries

  • Important part of a GIS project

    • Can be a part of your data preparation or final analysis

  • Data Queries (selecting data based on a question or criteria)

    • Attribute Query

    • Spatial Data Query


Attribute data query
Attribute Data Query

  • SQL (Structure Query Language) is used select records from an attribute table

  • Example of a SQL statement for retrieving data

    Select *

    Fromcounties

    WhereNAME = Monterey

  • Query Expressions

    • Boolean expressions

      • Combination of field, a value, and a logical operator (=, +, - , etc..)

    • Boolean connectors (AND, OR, XOR, NOT)

      • Connects two expressions


Query expressions
Query Expressions

Expression

  • Combination of field (column), value, and an operator

  • Example:

    • Name = Monterey

    • Pop2000 >=400,000

    • State_Name= Calfornia

      Connectors

  • Keywords that connect two expressions

    • State_Name = California AND Pop2000>= 400,000

    • State_Name = California OR Pop2000>= 400,000


And connector
AND Connector

  • State_Name = California AND Pop2000 >= 400,000

  • AND - satisfy both criteria - intersection


Or connector
OR Connector

  • State_Name = California OR Pop2000 >= 400,000

  • OR - satisfy either one or both criteria - union


Spatial data query
Spatial Data Query

3 Ways to select features spatially (by location)

  • Feature selection by cursor - (select features tools)

  • Feature selection by graphic - (draw a graphic and use it to select features)

  • Feature selection by spatial relationship

    • Containment (fall within a feature)

    • Intersect (intersect a feature)

    • Proximity ( within a specified distance)


Working with selected features
Working with selected features

  • create new selection

  • add to currently selected features

  • remove from currently selected features

  • select from currently selected features

You can add, remove or select from currently selected features using

location and attribute queries.


Isolating your selected features
Isolating your selected features

  • Permanently save your selected features

    • save as new data file (shapefile or geodatabase)

    • Right-click on layer  data  Export data

  • Temporary save your selected features

    • create a temp layer in your ArcMap project as

    • Right-click on layer  selection  create layer from selected features

    • One extra step ….

    • --- to create a .lyr file

    • Right-click on layer Save As Layer File


Summary of selection types
Summary of selection types

  • Select by attribute using SQL

    • In ArcMap you can find this in the:

      • Selection menu

      • Attribute table

      • Definition query – displays data only

        • Located in the layer’s properties

  • Spatial Query:

    • Manually using the cursor

    • Select by graphics

    • Select by Location dialog


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