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 SQL (Structure Query Language) is used

select records from an attribute table

Example of a SQL statement for retrieving data

Select *From countiesWhere NAME = 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 ExpressionsExpression

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

State_Name = California AND Pop2000 >= 400,000 AND - satisfy both criteria - intersection

OR Connector

State_Name = California OR Pop2000 >= 400,000 OR - satisfy either one or both criteria - union

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

1. create new selection 2. add to currently selected features3. remove from currently selected features4. select from currently selected features

You can add, remove or select from currently selected features using location and attribute queries.

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

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