Data Query in GIS

Flashcards reviewing thematic and spatial query concepts, SQL operators, and spatial relationships in GIS.

Data Query

A GIS functionality used for selecting a subset of features or computing a new characteristic based on specified conditions.

Thematic Query

Also known as an Attribute Query, it is the selection of features or records based on their aspatial characteristics using a DBMS query language such as SQL.

Spatial Query

A logical expression that selects geographic features based on their location or a specified spatial relationship relative to other features.

Structured Query Language (SQL)

A syntax-sensitive database language used to query data in DBMS and perform Select by Attributes in ArcGIS Pro.

Comparison Operators

SQL operators used to compare attribute values, including less than ($<$), greater than ($>$), equal to ($=$), and not equal ($<Shutdown>$).

Boolean Operators

Logical operators such as OR, AND, and NOT used in SQL to combine and evaluate multiple conditions simultaneously.

LIKE Operator

An SQL operator used instead of the equal ($=$) operator to construct partial string searches in combination with wildcards.

Wildcard (%)

A symbol used in SQL queries where the percent sign ($\%$) represents any sequence of zero, one, or multiple acceptable characters.

NULL

A keyword used in SQL to query records with missing or unknown values, which is always preceded by IS or IS NOT and is not equivalent to $0$.

Topology

A category of spatial queries concerning geometric relationship questions between features, specifically adjacency, containment, and connectivity.

Proximity Query

A spatial query category concerning straight-line or network distances between features.

Intersect (Spatial Relationship)

A spatial relationship where target layer features are selected if they intersect or cross a source layer feature.

Within a Distance

A spatial query selection method where input features are selected if they fall within a specified Search Distance parameter of a selecting feature.

Contains (Clementini)

A spatial relationship identical to COMPLETELY_CONTAINS, with the exception that if the selecting feature is entirely on the boundary of the input feature, it is not selected.

Within (Clementini)

A spatial relationship identical to WITHIN, except that if the entirety of the input feature is on the boundary of the selecting feature, it will not be selected.

Are Identical To

A spatial relationship where features in the input layer are selected if their geometry is identical to that of a selecting feature.

Boundary Touches

A spatial relationship where input features are selected if they have a boundary touching a selecting feature, provided no part of the input feature crosses the selecting feature boundary.

Share a Line Segment With

A spatial relationship requiring line or polygon features to share a line segment with a selecting feature to be selected.

Crossed by the Outline Of

A spatial relationship where line or polygon features are selected if they are crossed by the boundary outline of a selecting line or polygon feature.

Have Their Center In

A spatial relationship where features are selected if their center (centroid for polygon/multipoint or midpoint for line) falls inside a selecting feature.