ST_LineFromText function

The ST_LineFromText function takes a well-known text (WKT) format or a GeoJSON format of a linestring and, optionally, a spatial reference system identifier as input parameters and returns the corresponding linestring.

ST_LineFromText constructs a geometry from one of the following inputs:

A WKT format
GeoJSON format

The preferred version for this functionality is ST_LineString.

If the specified WKT format is null, then null is returned.

If the specified WKT or GeoJSON format is null, then null is returned.

For details about the supported formats, see Supported data formats.

Syntax

Parameters

wkt

A value of type VARCHAR or CLOB(2G) that contains the WKT format of the resulting linestring.

geojson

A value of type VARCHAR or CLOB(2G) that represents the resulting linestring using GeoJSON.

srs_id

A value of type INTEGER that identifies the spatial reference system for the resulting linestring.

If the srs_id parameter is omitted, the spatial reference system with the numeric identifier 4326 is used.

If srs_id does not identify a spatial reference system listed in the catalog view SYSGEO.ST_SPATIAL_REFERENCE_SYSTEMS, then an error is returned (SQLSTATE 38SU1).

Return type

ST_LineString

Example

In the following example, the lines of results have been reformatted for readability. The spacing in your results will vary according to your online display.

The following code uses the ST_LineFromText function to create and insert a line from a well-known text (WKT) line representation. The rows are inserted into the SAMPLE_LINES table with an ID and a line value in spatial reference system 1 in WKT format.



CREATE TABLE sample_lines(id SMALLINT, geometry ST_LineString)

INSERT INTO sample_lines(id, geometry)
VALUES
    (1110, ST_LineFromText('linestring(850 250, 850 850)', 1) ),
    (1111, ST_LineFromText('linestring empty', 1) )

SELECT id, cast(ST_AsText(geometry) AS varchar(60)) AS linestring
FROM   sample_lines

Results:



ID     LINESTRING
------ ------------------------------------------------------------
  1110 LINESTRING (850.000000 250.000000, 850.000000 850.000000)
  1111 LINESTRING EMPTY

Examples

Example 1:

In the following example, the lines of results have been reformatted for readability. The spacing in your results will vary according to your online display.



CREATE TABLE sample_lines(id SMALLINT, geometry ST_LineString)

INSERT INTO sample_lines(id, geometry)
VALUES
    (1110, ST_LineFromText('linestring(850 250, 850 850)', 1) ),
    (1111, ST_LineFromText('linestring empty', 1) )

SELECT id, cast(ST_AsText(geometry) AS varchar(60)) AS linestring
FROM   sample_lines

Results:



ID     LINESTRING
------ ------------------------------------------------------------
  1110 LINESTRING (850.000000 250.000000, 850.000000 850.000000)
  1111 LINESTRING EMPTY

Example 2:

In the following example, the lines of results have been reformatted for readability. The spacing in your results will vary according to your online display.

The following code uses the ST_LineFromText function to create and insert lines from a GeoJSON representation. The rows are inserted into the SAMPLE_LINES table with an ID and a line value in the default spatial reference system 4326 in GeoJSON format.


CREATE TABLE sample_lines(id SMALLINT, geometry ST_LineString)

INSERT INTO sample_lines(id, geometry)
VALUES
    (1110, ST_LineFromText('{ "type": "linestring", "coordinates": [[850, 250], [850, 850]] }') ),
    (1111, ST_LineFromText('{ "type": "linestring", "coordinates": [] }') )

SELECT id, cast(ST_AsText(geometry) AS varchar(75)) AS linestring
FROM   sample_lines

Results:


ID          GEOMETRY
----------- -----------------------------------------------------------------
       1110 LINESTRING (850.000000000 250.000000000, 850.000000000 850.000000000)
       1111 LINESTRING EMPTY