gis queries Flashcards
attribute query
an operation to extract specific records of information from a file based on values in the records
spatial query
operation to extract records from a data layer based on location relative to another data layer
logical operators
functions such as , or =, that compare values and generate a true or false result
expression
a statement containing field names, values, and/or functions used to extract records in a query or calculate values in a table
structured query language
an established syntax for creating logical expressions to extract records from a database acording to specified criteria
boolean operator
set of operators(AND, OR,NOT,XOR) that evaluate a pair of true or false propositions and return to a true or false result
venn diagram
a diagram used in set theory to portray sets and subsets
spatial operators
a set of functions that evaluate spatial relationships, including intersection, containment, and proximity, between sets of features
containment
the property of one feature including another in whole or in part
intersection
property of two features touching each other in whole or in part
proximity
the proximity of one feature being close to another feature
interactive selection
extracting one or more features by manually picking them from the screen with selection tools
select by attributes
to choose a subset of features or table objects based on the values in one or more attribute fields
select by location
to choose a subset of features based on their spatial relationshipto other features
buffer
delineated area within a specified distance of a feature
