I've built a database with postgreSQL with a few geometry columns. When I add some data to my non-geometry columns, I can see them in QGIS when I connect to my DB using postgis. Now, I want to add polygons to the existing entries with the editing tool in QGIS. That means, filling up the geometry columns in QGIS.
How can I do this? I've only heard about adding whole shapefiles to the database but not to add single features to a single column.