Hi, User in gis.stackoverflow tried to use SQL "select ST_Union(geometry)" for the Natural Earth SQLite db file from http://naciscdn.org/naturalearth/packages/natural_earth_vector.sqlite.zip.
The query yields an empty geometry because the NE database is written with FDO geometries instead of SpatiaLite geometries. What I wonder is that does GDAL user have any simple mean for getting informed if SQLite db is FDO or Spatialite. If SpatiaLite is present a clever enough user can use ogrinfo and check from https://www.gaia-gis.it/gaia-sins/spatialite-sql-latest.html#p16fdo that value 2 is returned in case when "both tables exist, and their layout is the one used by FDO/OGR" ogrinfo -sql "select CheckSpatialMetaData()" natural_earth_vector.sqlite INFO: Open of `natural_earth_vector.sqlite' using driver `SQLite' successful. Layer name: SELECT Geometry: None Feature Count: 1 Layer SRS WKT: (unknown) CheckSpatialMetaData(): Integer (0.0) OGRFeature(SELECT):0 CheckSpatialMetaData() (Integer) = 2 However, the one who knows to do that must be somewhat advanced GDAL and Spatialite user. -Jukka Rahkonen- _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
