ST_LineSubstring-PolarDB(PolarDB)-阿里云帮助中心

Returns a substring of a specified LineString.

Syntax

geometry  ST_LineSubstring(geometry  aLinestring , float8  startfraction , float8  endfraction);
geography ST_LineSubstring(geography  aLinestring , float8  startfraction , float8  endfraction);

Parameters

Parameter name	Description
aLinestring	The target LineString object.
startfraction	The start position.
endfraction	The end position.

Description

When startfraction and endfraction have the same value, this function is equivalent to ST_LineInterpolatePoint.
To apply this function to a MultiLineString object, you must first use ST_LineMerge to merge it.
This function supports 3D objects and does not delete the Z coordinate.
This function supports M coordinates.

Example

SELECT ST_AsText(ST_LineSubstring('LINESTRING(0 0,10 10)'::geometry,0.3,0.6));
      st_astext
---------------------
 LINESTRING(3 3,6 6)
(1 row)

--geography
SELECT ST_AsText(ST_LineSubstring('LINESTRING(0 0,10 10)'::geography,0.3,0.6));
                                   st_astext
--------------------------------------------------------------------------------
 LINESTRING(2.97227762767668 3.01417970957332,5.96094221033023 6.0199989936211)