Constructor functions in Lindorm spatial-temporal functions - Lindorm

This topic describes the constructor functions for spatio-temporal data. You can use these functions to build specific geometry objects or convert existing Well-known Text (WKT) strings and objects into other geometry formats.

Engines and versions

Constructor functions apply 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.

Important

Lindorm SQL must be version 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 that are supported by Lindorm GanosBase.

Function	Description
ST_GeomFromText	Returns a Geometry object that corresponds to the specified WKT string.
ST_LineFromMultiPoint	Returns a LineString object that corresponds to the specified MultiPoint object.
ST_MakePoint	Constructs a Point object.

ST_GeomFromText

Returns a Geometry object that corresponds to the specified WKT string.

Syntax

geometry ST_GeomFromText(string wkt)

Parameters

Parameter	Description
wkt	The specified WKT string.

Note

The Geometry object supports the following types: Point, LineString, Polygon, MultiPoint, MultiLineString, MultiPolygon, and GeometryCollection.
WKT strings that contain spatial reference system information are not supported. If the WKT format includes a Spatial Reference Identifier (SRID), you must store the SRID in a separate column. The SRID is used only as an identifier. The default SRID is 4326.
You can create an EMPTY object of any data type.

Examples

Example 1: The Geometry object is a Point.

SELECT ST_GeomFromText('POINT(1 1)') as geom;

The following result is returned:

+-------------+
|    geom     |
+-------------+
| POINT (1 1) |
+-------------+

Example 2: The Geometry object is a Polygon.

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: The Geometry object is EMPTY.

SELECT ST_GeomFromText('POLYGON EMPTY') as geom;

The following result is returned:

+---------------+
|     geom      |
+---------------+
| POLYGON EMPTY |
+---------------+

ST_LineFromMultiPoint

Returns a LineString object that corresponds to the specified MultiPoint object.

Syntax

geometry ST_LineFromMultiPoint(geometry aMultiPoint)

Parameters

Parameter	Description
aMultiPoint	The specified MultiPoint object. You can use the `ST_Collect` function to combine Point objects into a MultiPoint object.

Example

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

Constructs a Point object.

Syntax

geometry ST_MakePoint(double x, double y)

Parameters

Parameter	Description
x	The longitude value x. The value must be of the DOUBLE type. If you enter a value of the INTEGER or LONG type, it is automatically converted to the DOUBLE type.
y	The latitude value y. The value must be of the DOUBLE type. If you enter a value of the INTEGER or LONG type, it is automatically converted to the DOUBLE type.

Note

This function does not support setting a spatial reference system or creating 3D objects.

Example

SELECT ST_AsText(ST_MakePoint(1, 2)) as text;

The following result is returned:

+-------------+
|    text     |
+-------------+
| POINT (1 2) |
+-------------+