github
html_url | issue_url | id | node_id | user | created_at | updated_at | author_association | body | reactions | issue | performed_via_github_app |
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https://github.com/simonw/sqlite-utils/issues/399#issuecomment-1548913065 | https://api.github.com/repos/simonw/sqlite-utils/issues/399 | 1548913065 | IC_kwDOCGYnMM5cUomp | 433780 | 2023-05-16T03:11:03Z | 2023-05-16T03:11:52Z | NONE | Using this thread and some [other resources](https://sqlite-utils.datasette.io/en/stable/cli.html#spatialite-helpers) I managed to cobble together a couple of sqlite-utils lines to add a geometry column for a table that already has a lat/lng column. ``` # add a geometry column sqlite-utils add-geometry-column [db name] [table name] geometry --type POINT --srid 4326 # add a point for each row to geometry column sqlite-utils --load-extension=spatialite [db name] 'update [table name] SET Geometry=MakePoint(longitude, latitude, 4326);' ``` | { "total_count": 1, "+1": 1, "-1": 0, "laugh": 0, "hooray": 0, "confused": 0, "heart": 0, "rocket": 0, "eyes": 0 } |
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https://github.com/simonw/sqlite-utils/issues/399#issuecomment-1030807433 | https://api.github.com/repos/simonw/sqlite-utils/issues/399 | 1030807433 | IC_kwDOCGYnMM49cN-J | 6025893 | 2022-02-06T10:54:09Z | 2022-02-06T10:54:09Z | NONE | > Interesting that some accept an SRID and others do not - presumably GeomFromGeoJSON() always uses SRID=4326? The ewtk/ewkb ones don't accept an SRID is because ewkt encodes the SRID in the string, so you would do this with a wkt string: `GeomFromText('POINT(529090 179645)', 27700)` but for ewkt it would be `GeomFromEWKT('SRID=27700;POINT(529090 179645)')` The specs for KML and GeoJSON specify a Coordinate Reference System for the format - https://datatracker.ietf.org/doc/html/rfc7946#section-4 - https://docs.opengeospatial.org/is/12-007r2/12-007r2.html#1274 GML can specify the SRID in the XML at feature level e.g: ``` <gml:Point srsName="EPSG:27700"> <gml:coordinates>529090, 179645</gml:coordinates> </gml:Point> ``` There's a few more obscure formats in there, but broadly I think it is safe to assume an SRID param exists on the function for cases where the SRID is not implied by or specified in the input format. | { "total_count": 0, "+1": 0, "-1": 0, "laugh": 0, "hooray": 0, "confused": 0, "heart": 0, "rocket": 0, "eyes": 0 } |
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