ST_NumLineStrings function

The ST_NumLineStrings function takes a multilinestring as an input parameter and returns the number of linestrings that it contains.

If the specified multilinestring is null or is empty, then null is returned.

Syntax

Parameter

multilinestring: A value of type ST_MultiLineString that represents the multilinestring for which the number of linestrings is returned.

Return type

INTEGER

Example

Multilinestrings are stored in the SAMPLE_MLINES table. The ST_NumLineStrings function determines how many individual geometries are within each multilinestring.


CREATE TABLE sample_mlines (id INTEGER, geometry ST_MultiLineString)

INSERT INTO sample_mlines
  VALUES (110, ST_MultiLineString ('multilinestring 
       ( (33 2, 34 3, 35 6),
         (28 4, 29 5, 31 8, 43 12),
         (39 3, 37 4, 36 7))', 1) )
INSERT INTO sample_mlines
  VALUES (111, ST_MultiLineString ('multilinestring 
       ( (3 2, 4 3, 5 6),
         (8 4, 9 5, 3 8, 4 12))', 1) )

SELECT id, ST_NumLineStrings (geometry) NUM_WITHIN
  FROM sample_mlines

Results:


ID          NUM_WITHIN
----------- ----------
        110          3
        111          2