> It hit me today that a 1:n relationship can't be implemented just by a
> single foreign key constraint if n>0. I must have been sleeping very
> deeply not to notice this.
>
> E.g. if there is a table "list" and another table "list_item" and the
> relationship can be described as "every list has at least one
> list_item" (and every list_item can only be part of one list, but
> this is trivial).
<duck>
BTW: If every list_item could be part of any number (>0) of lists, you
get a n:m relationship with a join table and then the issue that each
list_item has to belong to at least one list arises as well.
Maybe there should also be a standard solution documented somewhere for
this case, too.
</duck>
Sincerely,
Wolfgang
