SQL to snap points to the closest line within a predefined radius

snap_points_to_lines.sql

-- Snap the points to their closest lines, found in the subquery below
SELECT
  point_id,
  line_id,
  ST_LINE_INTERPOLATE_POINT(line_geom,
  ST_Line_Locate_Point(line_geom, point_geom)) AS snapped_points --Create the snapped points
FROM 

--Subquery to find the closest line to each point (within a pre-defined raidus)
(
  SELECT DISTINCT ON
    (pt.id) ln.geom AS line_geom,
    pt.geom AS point_geom,
    ln.id AS line_id,
    pt.id AS point_id
  FROM
    point_table AS pt
  INNER JOIN
    line_table AS ln
  ON
    ST_DWithin(pt.geom,
      ln.geom,
      10) -- Snap points to lines within a 10m radius
  ORDER BY
    pt.id,
    ST_Distance(ln.geom,
      pt.geom)) AS closest_pnt; -- Here we order the result set by distance to find the closest line to each point, but as we have used SELECT DISTINCT, we only take the closest point.