ST_PointN(INT) method

Syntax

linestring-expression.ST_PointN(INT n)

Parameters

• n – The position of the element to return, from 1 to linestring-expression.ST_NumPoints().

Returns

ST_Point If the value of linestring-expression is the empty set, returns NULL. If the specified position n is less than 1 or greater than the number of points, returns NULL. Otherwise, returns the ST_Point value at position n.

Examples

• Example 1 – The following example returns the result Point (0 4).

  SELECT TREAT( Shape AS ST_LineString ).ST_PointN( 2 )
  FROM SpatialShapes WHERE ShapeID = 5

  The following example returns one row for each point in geom.

  BEGIN
  DECLARE geom ST_LineString;
  SET geom = NEW ST_LineString( 'LineString( 0 0, 1 0 )' );
  SELECT row_num, geom.ST_PointN( row_num )
  FROM sa_rowgenerator( 1, geom.ST_NumPoints() )
  ORDER BY row_num;
  END

  The example returns the following result set:

  row_num	geom.ST_PointN(row_num)
  1	Point (0 0)
  2	Point (1 0)

Standards

SQL/MM (ISO/IEC 13249-3: 2006) 7.2.5