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STIsPseudoMultiCurve

STIsPseudoMultiCurve — Checks if supplied @p_geometry is a GeometryCollection object containing only LineString, CircularString and CompoundCurve elements.

Function Specification.

Function [dbo].[STIsPseudoMultiCurve] (
                  @p_geometry geometry
         )
Returns bit

Description.

This function checks if the supplied @p_geometry is a GeometryCollection object containing only LineString, CircularString and CompoundCurve elements.

One cannot create a MultiLineString object where an element is a CircularString or CompoundCurve.

Any attempt to do so causes the GeometryType to be set to GeometryCollection rather than MultiLineString or MultiCurve.

If these sorts of GeometryCollection objects are not supported, it is impossible to represent a MultiLine object with a mix of CircularCurve and LineString types.

The function returns 1 (true) if provided geometry is a pseudo MultiCurve (or MultiLineString).

Parameters.

    @p_geometry (geometry) - GeometryCollection or MultiLineString.

Result.

This function returns 1 (true) if @_geometry is a pseudo MultiCurve, 0 (false) otherwise.

Example.

-- This is how SQL Server merges a LineString and a CircularString that do not touch
-- 
SELECT geometry::STGeomFromText('LINESTRING(0 0 0 5.6, 5 5 0 6.3,5 10 0 9.6)',0)
       .STUnion(
         geometry::STGeomFromText('CIRCULARSTRING(-0.5 -0.5 0 5.6,-0.2 -0.4 0 5.5, -0.1 -0.1 0 5.65)',0)
       ).AsTextZM() as MultiCurve;
GO

MultiCurve
--------------------------------------------------------------------------------------------------
GEOMETRYCOLLECTION (LINESTRING (5 10, 5 5, 0 0), CIRCULARSTRING (-0.5 -0.5, -0.2 -0.4, -0.1 -0.1))

-- Note that STUnion removes Z and M ordinates

-- Now put result through STIsPseudoMultiCurve
-- 
SELECT [dbo].STIsPseudoMultiCurve] ( geometry::STGeomFromText('GEOMETRYCOLLECTION (LINESTRING (5 10, 5 5, 0 0), CIRCULARSTRING (-0.5 -0.5, -0.2 -0.4, -0.1 -0.1))',0)) as isMultiCurve
GO

isMultiCurve
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