•If any geometry argument is not a syntactically well-formed geometry, an ER_GIS_INVALID_DATA  error occurs. 

•If any geometry argument is a syntactically well-formed geometry in an undefined spatial reference system (SRS), an ER_SRS_NOT_FOUND  error occurs. 

•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 to 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 to this section, with this exception: 

•If the geometry has an SRID value for a geographic spatial reference system (SRS), an ER_NOT_IMPLEMENTED_FOR_GEOGRAPHIC_SRS  error occurs. 

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)) | +------------------------------------+ 

