Hello,
When I execute a query that has a subquery behind a comparison operator
in its where-clause and the subquery returns an empty result, then the
result of the complete query is exactly how I want it: also an empty
result. Can I assume that this behaviour will stay the same in next
versions of sqlite? Perhaps this case is described somewhere on the
sqlite site, and I failed to find it and someone could point me to it?
An example of such a query is:
SELECT *
FROM ordercallback
WHERE account=@ACCOUNT
AND cb_seq_num>(
SELECT cb_seq_num
FROM ordercallback
WHERE cb_uuid=@CBUUID);
Why I ask is because that for example when the subquery returns more
than one result different databases do different things. Eg. MySQL
returns an error, sqlite does returns rows, etc. So I thought, perhaps
the behavior when the subquery returns not 1 but many or zero rows may
be undefined and could change in the future. I also searched a lot on
this subject on the web, but all that I find is that it is said that the
subquery is expected to return exactly one result which gives me the
impression that everything else may perhaps be undefined.
Thanks,
Gunnar
