A window-only function of a column, as saved (PLAN ยง11.9): a value of
another row of the partition, by the window's sort, so it needs a sort, and
it has the column's type, nullable. Last is the partition's last row, the
same on every row, as First is its first.
A window-only function of a column, as saved (PLAN ยง11.9): a value of another row of the partition, by the window's sort, so it needs a sort, and it has the column's type, nullable. Last is the partition's last row, the same on every row, as First is its first.