I have a large polygon table and a large point table in a postgis enabled PostgreSQL database. Each point has a unique reference number (double type). I want to spatial join the points to the polygons, but where multiple points are found within a polygon, I want ALL the reference numbers to be carried across into a new column in the polygon table (a string column called ref_numb_list). Multiple reference numbers would be delimited with commas.
This functionality is available in ArcGIS spatial joins where you're able to set a 'join' merge rule for an output column. But I need to do this in PostgreSQL, via pgAdmin.