Tom Lane schrieb am 08.08.2019 um 16:10:
> David's point is that the two occurrences of lead() don't mean the
> same thing. A window function is directly tied to the SELECT that
> it is in the select-list of, and its notion of next and previous
> rows is concerned with the set of rows that that SELECT's FROM-clause
> generates. In this example, the inner SELECT has an empty FROM that
> returns one row, so the lead() in that SELECT doesn't do anything
> useful.
Ah! Now I get it ;)
Thanks for clearing that up.
> You could probably get where you want to go with something along
> the lines of
Yes, that's what I did in the end (see my initial post)