Queries Flashcards
Attribute queries test for what?
Table values (such as population)
Spatial queries test for what?
Spatial relationships
Each row in an attribute table represents a…?
Record (such as a site)
Each column in an attribute table represents a…?
Field (categories such as NRHP status)
What happens in an interactive query
The user visually identifies the desired features in a map or records in an attribute table
Operators
Act on objects to produce a result
What do arithmetic operators act on?
Numbers (+-x^)
Logical operators do what?
Test conditions, return true or false (= > < )
What are Boolean operators?
AND OR XOR NOT, test pairs of conditions and return true or false
In an attribute query, expressions are executed using what language?
SQL, structured query language
Spatial queries test what?
The spatial relation between two layers
What are the three basic operators that test spatial relationships?
Intersect, Contains/within, and proximity
What is a difference between the contains and completely contains operators?
The contains operator permits the feature to share a boundary
What is the importance of the target layer when executing a spatial query?
It’s the layer features will be selected from
What is the source layer in a spatial query
The layer that the target features are compared to
Spatial queries are done using what tool?
The Select by Layer tool
