Joining Spatial and Non-Spatial Data

Data integration

is the process of combining information from different data sources into a single usable dataset.

Spatial data

contains information about the location and geometry of geographic features.

points, lines, or polygons

Spatial data can represent features as

Non-spatial data

contains descriptive information without geographic geometry.

Spatial data

include locations of schools, roads, buildings, rivers, barangay boundaries, and land parcels.

Non-spatial data

include population, household counts, income, land-use classifications, survey results, and demographic information.

common field

A non-spatial table can be connected to spatial data when both datasets contain a

table join

is the process of combining records from two tables using a common attribute.

join field

is the field used to match records between the spatial and non-spatial tables.

common field

is an attribute field that exists in both datasets and is used to establish the relationship between them.

primary key

is a field containing a unique identifier for each record in a table.

foreign key

is a field in one table that refers to the identifier of a record in another table.

foreign key

allows information from one table to be associated with records in another table.

one-to-one relationship

occurs when one record in the first table corresponds to exactly one record in the second table.

one-to-many relationship

occurs when one record in the first table corresponds to multiple records in the second table.

many-to-one relationship

occurs when multiple records in one table correspond to a single record in another table.

many-to-many relationship

occurs when multiple records in one table correspond to multiple records in another table.

one-to-one

A basic attribute join is most straightforward when the relationship is

Missing match

occurs when a value in the spatial table has no corresponding value in the non-spatial table.

Duplicate identifier

occurs when an identifier that should be unique appears multiple times.

Data-type mismatch

occurs when the join fields use incompatible data types.

Formatting mismatch

occurs when equivalent values are written differently.

Incorrect join field

occurs when a field that does not uniquely or correctly identify features is selected for the join.