Refresh SpatiaLite documentation

[simonw]

https://docs.datasette.io/en/0.55/spatialite.html was written before I had tools like geojson-to-sqlite and shapefile-to-sqlite.

[simonw]

I have a better recipe for using spatial indexes now on https://simonwillison.net/2021/Jan/24/drawing-shapes-spatialite/

select
  AsGeoJSON(geometry), *
from
  CPAD_2020a_SuperUnits
where
  PARK_NAME like '%mini%' and
  Intersects(GeomFromGeoJSON(:freedraw), geometry) = 1
  and CPAD_2020a_SuperUnits.rowid in (
    select
      rowid
    from
      SpatialIndex
    where
      f_table_name = 'CPAD_2020a_SuperUnits'
      and search_frame = GeomFromGeoJSON(:freedraw)
  )

[simonw]

This will give you back an additional column of GeoJSON. You can copy and paste GeoJSON from this column into the debugging tool at geojson.io to visualize it on a map.

That should promote datasette-leaflet-geojson instead.

[simonw]

That rivers example in the tutorial would work a lot better with a live demo.

[simonw]

Useful tutorial series from 2012: https://northredoubt.com/n/2012/01/20/spatialite-speed-test/