Name
ST_NumCurves — Return the number of component curves in a CompoundCurve.
Synopsis
integer ST_NumCurves(geometry a_compoundcurve);
描述
Return the number of component curves in a CompoundCurve, zero for an empty CompoundCurve, or NULL for a non-CompoundCurve input.
该方法实现了SQL/MM规范。 SQL-MM 3: 8.2.6, 8.3.5
该函数支持 3d 并且不会丢失 z-index。
示例
-- Returns 3
SELECT ST_NumCurves('COMPOUNDCURVE(
(2 2, 2.5 2.5),
CIRCULARSTRING(2.5 2.5, 4.5 2.5, 3.5 3.5),
(3.5 3.5, 2.5 4.5, 3 5, 2 2)
)');
-- Returns 0
SELECT ST_NumCurves('COMPOUNDCURVE EMPTY');