This topic describes the geometry constructor functions supported by Lindorm Ganos.
Applicable engines and versions
The constructor functions described in this topic are applicable only to LindormTable.
The aggregate functions described in this topic are supported by LindormTable 2.6.5 and later versions. For more information about how to view or upgrade the version of LindormTable, see Release notes of LindormTable and Upgrade the minor engine version of a Lindorm instance.
The Lindorm SQL version must be 2.6.8 or later. For more information about how to view the Lindorm SQL version, see SQL versions.
Functions
The following table lists the constructor functions supported by Lindorm Ganos.
Function | Description |
Constructs a geometry object based on the specified Well-known Text (WKT) string. | |
Constructs a LineString object based on the specified MultiPoint object. | |
Constructs a point object. |
ST_GeomFromText
The ST_GeomFromText function constructs a geometry object based on the specified Well-known Text (WKT) string.
Syntax
geometry ST_GeomFromText(string wkt)Parameters
Parameter | Description |
wkt | The WKT string based on which you want to construct a geometry object. |
You can construct the following types of objects by calling this function: Point, LineString, Polygon, MultiPoint, MultiLineString, MultiPolygon and GeometryCollection.
This function does not support WKT strings that include Spatial Reference Identifiers (SRIDs). You can create a column in the database to store the SRIDs (4326 by default) of the geometry objects that you construct.
You can construct an empty geometry object of any supported data type.
Examples
Example 1: Construct a point object.
SELECT ST_GeomFromText('POINT(1 1)') as geom;The following result is returned:
+-------------+ | geom | +-------------+ | POINT (1 1) | +-------------+Example 2: Construct a polygon object.
SELECT ST_GeomFromText('POLYGON (( 1 1, 1 2, 2 2, 2 1, 1 1))') AS poly;The following result is returned:
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ | poly | +----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ | 0020000003000010E600000001000000053FF00000000000003FF00000000000003FF000000000000040000000000000004000000000000000400000000000000040000000000000003FF00000000000003FF00000000000003FF0000000000000 | +----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+Example 3: Construct an empty polygon object.
SELECT ST_GeomFromText('POLYGON EMPTY') as geom;The following result is returned:
+---------------+ | geom | +---------------+ | POLYGON EMPTY | +---------------+
ST_LineFromMultiPoint
The ST_LineFromMultiPoint function constructs a LineString object based on the specified MultiPoint object.
Syntax
geometry ST_LineFromMultiPoint(geometry aMultiPoint)Parameters
Parameter | Description |
aMultiPoint | You can call the |
Examples
SELECT ST_AsText(ST_LineFromMultiPoint(ST_Collect(ST_MakePoint(1,2),ST_MakePoint(3,4),ST_MakePoint(5,6)))) AS astext;The following result is returned:
+-------------------------+
| astext |
+-------------------------+
| LINESTRING(1 2,3 4,5 6) |
+-------------------------+ST_MakePoint
The ST_MakePoint function constructs a point object.
Syntax
geometry ST_MakePoint(double x, double y)Parameters
Parameter | Description |
x | The longitude of the point object that you want to construct. The value of this parameter is a number of the DOUBLE type. If you specify a number of the INTEGER or LONG type, it is automatically converted to the DOUBLE type. |
y | The latitude of the point object that you want to construct. The value of this parameter is a number of the DOUBLE type. If you specify a number of the INTEGER or LONG type, it is automatically converted to the DOUBLE type. |
This function can be used to construct only 2D point objects without Spatial Reference System (SRS) information.
Examples
SELECT ST_AsText(ST_MakePoint(1, 2)) as text;The following result is returned:
+-------------+
| text |
+-------------+
| POINT (1 2) |
+-------------+