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MySQL 8.0 Reference Manual  /  ...  /  LineString and MultiLineString Property Functions

Pre-General Availability Draft: 2017-11-24

12.15.7.3 LineString and MultiLineString Property Functions

A LineString consists of Point values. You can extract particular points of a LineString, count the number of points that it contains, or obtain its length.

Some functions in this section also work for MultiLineString values.

Unless otherwise specified, functions in this section handle their arguments as follows:

  • If any argument is NULL or a geometry argument is an empty geometry, the return value is NULL.

  • Otherwise, the return value is non-NULL.

These functions are available for obtaining linestring properties:

  • ST_EndPoint(ls)

    Returns the Point that is the endpoint of the LineString value ls.

    ST_EndPoint() handles its arguments as described in the introduction of this section.

    mysql> SET @ls = 'LineString(1 1,2 2,3 3)';
    mysql> SELECT ST_AsText(ST_EndPoint(ST_GeomFromText(@ls)));
    +----------------------------------------------+
    | ST_AsText(ST_EndPoint(ST_GeomFromText(@ls))) |
    +----------------------------------------------+
    | POINT(3 3)                                   |
    +----------------------------------------------+
  • ST_IsClosed(ls)

    For a LineString value ls, ST_IsClosed() returns 1 if ls is closed (that is, its ST_StartPoint() and ST_EndPoint() values are the same).

    For a MultiLineString value ls, ST_IsClosed() returns 1 if ls is closed (that is, the ST_StartPoint() and ST_EndPoint() values are the same for each LineString in ls).

    ST_IsClosed() returns 0 if ls is not closed, and NULL if ls is NULL.

    ST_IsClosed() handles its arguments as described in the introduction of this section.

    mysql> SET @ls1 = 'LineString(1 1,2 2,3 3,2 2)';
    mysql> SET @ls2 = 'LineString(1 1,2 2,3 3,1 1)';
    
    mysql> SELECT ST_IsClosed(ST_GeomFromText(@ls1));
    +------------------------------------+
    | ST_IsClosed(ST_GeomFromText(@ls1)) |
    +------------------------------------+
    |                                  0 |
    +------------------------------------+
    
    mysql> SELECT ST_IsClosed(ST_GeomFromText(@ls2));
    +------------------------------------+
    | ST_IsClosed(ST_GeomFromText(@ls2)) |
    +------------------------------------+
    |                                  1 |
    +------------------------------------+
    
    mysql> SET @ls3 = 'MultiLineString((1 1,2 2,3 3),(4 4,5 5))';
    
    mysql> SELECT ST_IsClosed(ST_GeomFromText(@ls3));
    +------------------------------------+
    | ST_IsClosed(ST_GeomFromText(@ls3)) |
    +------------------------------------+
    |                                  0 |
    +------------------------------------+
  • ST_Length(ls)

    Returns a double-precision number indicating the length of the LineString or MultiLineString value ls in its associated spatial reference. The length of a MultiLineString value is equal to the sum of the lengths of its elements.

    ST_Length() handles its arguments as described in the introduction of this section.

    mysql> SET @ls = 'LineString(1 1,2 2,3 3)';
    mysql> SELECT ST_Length(ST_GeomFromText(@ls));
    +---------------------------------+
    | ST_Length(ST_GeomFromText(@ls)) |
    +---------------------------------+
    |              2.8284271247461903 |
    +---------------------------------+
    
    mysql> SET @mls = 'MultiLineString((1 1,2 2,3 3),(4 4,5 5))';
    mysql> SELECT ST_Length(ST_GeomFromText(@mls));
    +----------------------------------+
    | ST_Length(ST_GeomFromText(@mls)) |
    +----------------------------------+
    |                4.242640687119286 |
    +----------------------------------+
  • ST_NumPoints(ls)

    Returns the number of Point objects in the LineString value ls.

    ST_NumPoints() handles its arguments as described in the introduction of this section.

    mysql> SET @ls = 'LineString(1 1,2 2,3 3)';
    mysql> SELECT ST_NumPoints(ST_GeomFromText(@ls));
    +------------------------------------+
    | ST_NumPoints(ST_GeomFromText(@ls)) |
    +------------------------------------+
    |                                  3 |
    +------------------------------------+
  • ST_PointN(ls, N)

    Returns the N-th Point in the Linestring value ls. Points are numbered beginning with 1.

    ST_PointN() handles its arguments as described in the introduction of this section.

    mysql> SET @ls = 'LineString(1 1,2 2,3 3)';
    mysql> SELECT ST_AsText(ST_PointN(ST_GeomFromText(@ls),2));
    +----------------------------------------------+
    | ST_AsText(ST_PointN(ST_GeomFromText(@ls),2)) |
    +----------------------------------------------+
    | POINT(2 2)                                   |
    +----------------------------------------------+
  • ST_StartPoint(ls)

    Returns the Point that is the start point of the LineString value ls.

    ST_StartPoint() handles its arguments as described in the introduction of this section.

    mysql> SET @ls = 'LineString(1 1,2 2,3 3)';
    mysql> SELECT ST_AsText(ST_StartPoint(ST_GeomFromText(@ls)));
    +------------------------------------------------+
    | ST_AsText(ST_StartPoint(ST_GeomFromText(@ls))) |
    +------------------------------------------------+
    | POINT(1 1)                                     |
    +------------------------------------------------+

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