问题描述
CREATE TABLE SomeShapes AS
SELECT ash.id,ash.Geometry
FROM AllShapes ash
WHERE ash.id = 30
$ b $但是,这会返回一个正常表,因此当我尝试将它加载到GIS程序(QGIS)中时,它不会显示几何图形。如何声明geometry列包含几何?
您需要创建一个非空间表,然后添加几何
列到它。
它不能在一步完成( create table as select
)。从:
<$ (
id INTEGER NOT NULL
PRIMARY KEY AUTOINCREMENT,
name TEXT NOT NULL,
measured_value DOUBLE NOT NULL); pre> CREATE TABLE test_geom
SELECT AddGeometryColumn('test_geom','Geometry',4326,'POINT','XY');
另外,考虑到您可能需要使用改善性能
SELECT CreateSpatialIndex('test_geom','Geometry');
I am creating a new table through a SQL query from a spatial table:
CREATE TABLE SomeShapes AS
SELECT ash.id, ash.Geometry
FROM AllShapes ash
WHERE ash.id = 30
However, this returns a "normal" table, so when I try to load it in a GIS program (QGIS), it doesn't show the geometry. How do I declare that the geometry column contains, well, geometry?
You need to create a "non-spatial" table, and then add the Geometry
column to it.
Then, you can insert data into your table.
It can't be done in one single step (create table as select
). From the documentation:
CREATE TABLE test_geom (
id INTEGER NOT NULL
PRIMARY KEY AUTOINCREMENT,
name TEXT NOT NULL,
measured_value DOUBLE NOT NULL);
SELECT AddGeometryColumn('test_geom', 'Geometry', 4326, 'POINT', 'XY');
Also, take into account that you may want to use spatial indexes to improve the performance
SELECT CreateSpatialIndex('test_geom', 'Geometry');
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