that doesn't work:
eingangsrechnungenBindingSource.Sort = "ID ASC AND angelegt_am DESC";
eingangsrechnungenBindingSource.Sort = "ID ASC && angelegt_am DESC";
is has to be:
eingangsrechnungenBindingSource.Sort = "ID ASC, angelegt_am DESC";
The Sort property is a case-sensitive string that specifies the column names used to sort the rows, along with the sort direction. Columns are sorted ascending by default. Multiple columns can be sepa…