I have some different kinds of geometry (Polygons and line strings) stored in my mysql database. On different rows.
I know I can retrieve the envelope of one row with:
SELECT Envelope(zoneShape) FROM geometryTable WHERE refid=4
If there are three different shapes associated with reference id 4, i'm getting three results, obviously.
How can I (preferably with one sql query) get the envelope/MBR of all the geometry with e.g. refid=4?