collections by extracting all vertex points of all components of the collection, creating a MultiPoint value from them, and computing its convex hull. 

ST_ConvexHull()  handles its arguments as described in the introduction to this section, with this exception: 

•The return value is NULL  for the additional condition that the argument is an empty geometry collection. 

mysql> SET @g = ’MULTIPOINT(5 0,25 0,15 10,15 25)’; mysql> SELECT ST_AsText(ST_ConvexHull(ST_GeomFromText(@g))); +-----------------------------------------------+ | ST_AsText(ST_ConvexHull(ST_GeomFromText(@g))) | +-----------------------------------------------+ | POLYGON((5 0,25 0,15 25,5 0)) | +-----------------------------------------------+ 

• ST_Difference( g1 , g2 ) 

Returns a geometry that represents the point set difference of the geometry values g1  and g2 . The result is in the same SRS as the geometry arguments. 

As of MySQL 8.0.26, ST_Difference()  permits arguments in either a Cartesian or a geographic SRS. Prior to MySQL 8.0.26, ST_Difference()  permits arguments in a Cartesian SRS only; for arguments in a geographic SRS, an ER_NOT_IMPLEMENTED_FOR_GEOGRAPHIC_SRS  error occurs. 

ST_Difference()  handles its arguments as described in the introduction to this section. 

mysql> SET @g1 = Point(1,1), @g2 = Point(2,2); mysql> SELECT ST_AsText(ST_Difference(@g1, @g2)); +------------------------------------+ | ST_AsText(ST_Difference(@g1, @g2)) | +------------------------------------+ | POINT(1 1) | +------------------------------------+ 

• ST_Intersection( g1 , g2 ) 

Returns a geometry that represents the point set intersection of the geometry values g1  and g2 . The result is in the same SRS as the geometry arguments. 

As of MySQL 8.0.27, ST_Intersection()  permits arguments in either a Cartesian or a geographic SRS. Prior to MySQL 8.0.27, ST_Intersection()  permits arguments in a Cartesian SRS only; for arguments in a geographic SRS, an ER_NOT_IMPLEMENTED_FOR_GEOGRAPHIC_SRS  error occurs. 

ST_Intersection()  handles its arguments as described in the introduction to this section. 

mysql> SET @g1 = ST_GeomFromText(’LineString(1 1, 3 3)’); mysql> SET @g2 = ST_GeomFromText(’LineString(1 3, 3 1)’); mysql> SELECT ST_AsText(ST_Intersection(@g1, @g2)); +--------------------------------------+ | ST_AsText(ST_Intersection(@g1, @g2)) | +--------------------------------------+ | POINT(2 2) | +--------------------------------------+ 

• ST_LineInterpolatePoint( ls , fractional_distance ) 

This function takes a LineString  geometry and a fractional distance in the range [0.0, 1.0] and returns the Point  along the LineString  at the given fraction of the distance from its start point to its endpoint. 

