[chaley]

Originally Posted by nynaevelan

I looked there and it did not offer any enlightenment to either of my questions. If I've missed it, please point me in the right direction. That was the first place I looked.

You asked:

Ok, so does anyone know if it is possible to export data from the custom fields??

The command calibredb list can export data from the custom fields. As the help says:

Usage: calibredb.exe list [options]
...
Options:
...
  -f FIELDS, --fields=FIELDS
                        The fields to display when listing books in the
                        database. Should be a comma separated list of fields.
                        Available fields: (... field names printed)
                        Default: title,authors. The special field "all" can be
                        used to select all fields. Only has effect in the text
                        output format.

For example, if you have a column named #foo, then
calibredb list -f *foo --separator ,
will output a (sort-of) CSV list of the foo field.

And yes, you must replace the '#' with a '*' when naming custom fields.