School of Geography FACULTY OF ENVIRONMENT Querying with ArcGIS

What is Querying? A request to select features or records from a database Often written as a statement or logical expression Types of queries: Interactive click on features using the Identify tool Find tool Distance tool Select by Attribute (SQL query) Select by Location (spatial query) Select by Graphic

Selection Tools Select and clear individual features from the Tools toolbar Various selection options from the Selection menu

Dynamic Linkage

Selection Options in ArcMap Specify interactive selection method + Selection Option (Selection  Options)

Select by Attribute Uses an SQL where clause to select features Save and reload selection expressions Selected features in blue Right click in the Field box

Other Features Search on a text name – enclose in single brackets Use wildcard characters - % or * for any length; _ for one character in combination with LIKE Use Boolean operators to look in more than one column, i.e. AND, OR, NOT, etc. Is NULL – to search for null values Get Unique Values + Go To: Substring (“STATE_NAME”,1,2) = ‘Te’

Select by Location Is a spatial query Use features in one layer to select features in another Examples are to select features in A that are: Completely contain B Intersect with B Are within a specified distance of B Are completely within B Etc.

Example of a Query by Location

Results of the Query Addresses within 50m of motorwayFurther refined to choose only dwellings

Select by Graphics Draw a graphic to select features Works with interactive selection methods

Save Selection Or export as a shapefile Data  Export Data

Querying in ArcMap Hands-on Exercise #8