SpatiaLite SQL statement to find points in a line buffer

A typical GIS spatial query is to find all the point features in a buffer around a linear feature. This can be easily achieved using SpatiaLite database also. The following illustrates the workflow using two SpatiaLite feature tables - nodes and segments.

Using any SpatiaLite interface (graphical or command line interface), simply type in the following SQL statement to create a 50 meter buffer around the line segment feature using the spatial operator ST_Buffer:

SELECT ST_Buffer(Geometry, 50) AS buffer 
FROM segments
WHERE name='line1'


The screenshot below shows how the 50 meter buffer looks like on a map.

To identify all the point nodes within the buffer, we can wrap the buffer statement in a more complex SQL statement:

SELECT a.* FROM nodes AS a,
(
SELECT buffer FROM
(
SELECT ST_Buffer(Geometry, 50) AS buffer 
FROM segments
WHERE name='line1'
) AS b
)
WHERE ST_Contains(buffer, a.Geometry)

The screenshot shows how the results are like on a map.