>>>>> "Andrew" == Andrew Gierth <andrew@tao11.riddles.org.uk> writes:
>>> Whole-row vars when constructed never contain the null value.
David> ...but what does this mean in end-user terms?
Andrew> It means for example that this query:
Andrew> select y from x left join y on (x.id=y.id) where y is null;
Andrew> would always return 0 rows.
On second thoughts I'll take this one back. Specifying that whole-row
vars don't contain the null value when constructed doesn't actually
result in no rows, since the construction is logically below the join;
and hence even with that rule in place, the query would return a row for
each non-matched "x" row.
--
Andrew (irc:RhodiumToad)
