ST_ToCurve method for type ST

geometry-expression.ST_ToCurve()

ST_Curve If the geometry-expression is of type ST_Curve, return the geometry-expression. If the geometry-expression is a geometry collection with a single element of type ST_Curve, return that element. If the geometry-expression is the empty set, return an empty set of type ST_LineString. Otherwise, raise an exception condition.
The spatial reference system identifier of the result is the same as the spatial reference system of the geometry-expression.

Converts the geometry to a curve. The logic is equivalent to that used for CAST( geometry-expression AS ST_Curve ).

If geometry-expression is already known to be an ST_Curve value, it is more efficient to use TREAT( geometry-expression AS ST_Curve ) than the ST_ToCurve method.

Note

By default, ST_ToCurve uses the original format for a geometry, if it is available. Otherwise, the internal format is used. For more information about internal and original formats, see STORAGE FORMAT clause, CREATE SPATIAL REFERENCE SYSTEM statement.

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

The following example returns the result LineString (0 0, 1 1, 2 0).

SELECT NEW ST_GeomCollection( 'GeometryCollection(LineString(0 0, 1 1, 2 0))' ).ST_ToCurve()

ST_ToCurve method for type ST_Geometry

Syntax

Returns

Remarks

Note

See also

Standards and compatibility

Example