• 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 to this section. 

## 12.17.7.4 Polygon and MultiPolygon Property Functions 

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

Functions in this section return properties of Polygon  or MultiPolygon  values. 

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

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

•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. 

•For functions that take multiple geometry arguments, if those arguments are not in the same SRS, an ER_GIS_DIFFERENT_SRIDS  error occurs. 

•Otherwise, the return value is non- NULL . 

These functions are available for obtaining polygon properties: 

• ST_Area({ poly | mpoly }) 

Returns a double-precision number indicating the area of the Polygon  or MultiPolygon  argument, as measured in its spatial reference system. 

As of MySQL 8.0.13, ST_Area()  handles its arguments as described in the introduction to this section, with these exceptions: 

•If the geometry is geometrically invalid, either the result is an undefined area (that is, it can be any number), or an error occurs. 

•If the geometry is valid but is not a Polygon  or MultiPolygon  object, an ER_UNEXPECTED_GEOMETRY_TYPE  error occurs. 

•If the geometry is a valid Polygon  in a Cartesian SRS, the result is the Cartesian area of the polygon. 

•If the geometry is a valid MultiPolygon  in a Cartesian SRS, the result is the sum of the Cartesian area of the polygons. 

•If the geometry is a valid Polygon  in a geographic SRS, the result is the geodetic area of the polygon in that SRS, in square meters. 

•If the geometry is a valid MultiPolygon  in a geographic SRS, the result is the sum of geodetic area of the polygons in that SRS, in square meters. 

