• ST_IsSimple( g ) 

Returns 1 if the geometry value g  is simple according to the ISO SQL/MM Part 3: Spatial  standard. ST_IsSimple()  returns 0 if the argument is not simple. 

The descriptions of the instantiable geometric classes given under Section 11.4.2, “The OpenGIS Geometry Model”  include the specific conditions that cause class instances to be classified as not simple. 

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

•If the geometry has a geographic SRS with a longitude or latitude that is out of range, an error occurs: 

• If a longitude value is not in the range ( − 180, 180], an ER_GEOMETRY_PARAM_LONGITUDE_OUT_OF_RANGE  error occurs ( ER_LONGITUDE_OUT_OF_RANGE  prior to MySQL 8.0.12). 

• If a latitude value is not in the range [ − 90, 90], an ER_GEOMETRY_PARAM_LATITUDE_OUT_OF_RANGE  error occurs ( ER_LATITUDE_OUT_OF_RANGE prior to MySQL 8.0.12). 

Ranges shown are in degrees. The exact range limits deviate slightly due to floating-point arithmetic. 

• ST_SRID( g  [, srid ]) 

With a single argument representing a valid geometry object g , ST_SRID()  returns an integer indicating the ID of the spatial reference system (SRS) associated with g . 

With the optional second argument representing a valid SRID value, ST_SRID()  returns an object with the same type as its first argument with an SRID value equal to the second argument. This only sets the SRID value of the object; it does not perform any transformation of coordinate values. 

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

•For the single-argument syntax, ST_SRID()  returns the geometry SRID even if it refers to an undefined SRS. An ER_SRS_NOT_FOUND  error does not occur. 

ST_SRID( g , target_srid )  and ST_Transform( g , target_srid )  differ as follows: 

• ST_SRID()  changes the geometry SRID value without transforming its coordinates. 

• ST_Transform()  transforms the geometry coordinates in addition to changing its SRID value. 

mysql> SET @g = ST_GeomFromText(’LineString(1 1,2 2)’, 0); mysql> SELECT ST_SRID(@g); +-------------+ | ST_SRID(@g) | +-------------+ | 0 | +-------------+ mysql> SET @g = ST_SRID(@g, 4326); mysql> SELECT ST_SRID(@g); +-------------+ | ST_SRID(@g) | +-------------+ | 4326 | 

