multicurve-expression.ST_Length([ unit-name])

The ST_Length method returns the length of a multicurve in the units identified by the unit-name parameter. If the curve is empty, then NULL is returned.

If the curve contains Z values, these are not considered when computing the length of the geometry.

• ST_Length method for type ST_Curve

The following example creates a multicurve and uses ST_Length to find the length of the geometry, returning the value PI+1.

SELECT NEW ST_MultiCurve( 
	    NEW ST_LineString('LineString (0 0, 1 0)' ), 
	    NEW ST_CircularString( 'CircularString( 0 0, 1 1, 2 0)' ) )
	.ST_Length()

The following example creates a multicurve and an example unit of measure (example_unit_halfmetre). The ST_Length method finds the length of the geometry in this unit of measure, returning the value 6.0.

begin
    declare @multi_curve ST_MultiCurve;
    CREATE SPATIAL UNIT OF MEASURE IF NOT EXISTS  "example_unit_halfmetre" TYPE LINEAR CONVERT USING .5;
    set @multi_curve = NEW ST_MultiCurve( 
	    NEW ST_LineString('LineString (0 0, 1 0)' ), 
	    NEW ST_LineString('LineString (0 2, 2 2)' ) );
    SELECT @multi_curve.ST_Length('example_unit_halfmetre');
end