perty-functions.html\n\n','mysql> SET @poly =\n       \'Polygon((0 0,0 3,3 3,3 0,0 0),(1 1,1 2,2 2,2 1,1 1))\';\nmysql> SELECT ST_NumInteriorRings(ST_GeomFromText(@poly));\n+---------------------------------------------+\n| ST_NumInteriorRings(ST_GeomFromText(@poly)) |\n+---------------------------------------------+\n|                                           1 |\n+---------------------------------------------+\n','http://dev.mysql.com/doc/refman/5.7/en/gis-polygon-property-functions.html');