New answers tagged spatialite
Your problem is very easy to resolve because the problem is only in the documentation. https://www.gaia-gis.it/gaia-sins/spatialite-sql-latest.html is indeed claiming that ST_Centroid requires Surface but it is not true and you can just feed in your MultiPoints as they are. I made a a following test with spatialite-gui versions 1.8.0 and 2.0.0: Query: ...
Lets start with a simple example: spatialite> CREATE TABLE gis193636 (id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, flag INTEGER NOT NULL); spatialite> SELECT AddGeometryColumn( 'gis193636', 'geom', 0, 'MULTIPOINT', 'XY', 1); 1 spatialite> INSERT INTO gis193636 (flag, geom) VALUES (1, GeomFromText('MULTIPOINT((0 0))', ...
There is a plugin which allows this to be done, turn on experimental plugins. Why can't I edit attribute table imported through 'text as layer'
Found the solution after I explored the documentation a bit more. https://www.gaia-gis.it/gaia-sins/spatialite-cookbook/html/c.html Unfortunately, the cookbook part was more about how to use spatial queries instead of how to create software using the spatialite library, with an incomplete description on how to create the metatables. The missing piece is ...
Here is a step-wise process. Queries were made with Spatialite-gui and visualizations with OpenJUMP. Take some points into table "points" with an attribute "radius". Buffer points by taking the radius from an attribute with SQL CREATE TABLE "buffers" AS SELECT ST_Buffer("geometry", "radius") as geometry FROM points; Union the buffer areas with SQL ...
You could to use Dissolve Tool But, perhaps you could to create a buffer using the parameter: Dissolve result=YES
In SQL, it is an aggregation query. You can do something like: Select st_Union(geom) from your_table group by the_attribute_which_make_each_group
In QGIS you'd use the merge shapefiles function, just be sure to choose the correct couples/triplets/whatever. From the program menu, Vector -> Data management tools -> merge shapefiles
As I've got a similar problem with Geopackage spatial views I thought I'd share what I've seen elsewhere. Some people are reporting that if you select both the ROWID column and geometry column and alias both using " as " in the view SQL, but give them aliases that are exactly the same as the column names, then this fixes the problem in Spatialite. This ...
Try UNION ALL for collecting all the geometries before running ST_COLLECT. SELECT ST_Collect(geometry) FROM (SELECT geometry from tbl1 UNION ALL SELECT geometry from tbl2 UNION ALL SELECT geometry from tbl3 UNION ALL SELECT geometry from tbl4);
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