Also, does an empty list always evaluate to false? I guess it should... I'm just confused because it appears that this evaluation is not always doing what I expect. Maybe the problem lies elsewhere....

In the case in question, there was no need to get the actual data, the only question was if there were any rows returned.

In that case you could do with a different approach -



my $sql = "SELECT count(*) FROM table WHERE .... ";
...
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This query will return a single row containing the count of matching rows (row count) in the table. I believe this is the most efficient and portable way to determine the number of rows, and the fastest too.

and the fastest too.

Perhaps the most intuitive, but not necessarily the fastest (update: the fastest way to determine if there are any rows, that is, as the OP asked for). If your database is able to return rows as they're found (i.e. it doesn't have to return the entire result set like MySQL), and if there are any rows, it can be faster to do a select 1 from table... than to do a select count(*) from table....

Also, does an empty list always evaluate to false?

I am delighted at finding myself inconsistent! I feel passionately that "returns an array" is bad documentation, but "returns an empty list" doesn't make me blink twice, even though from a language-semantics point of view, a routine in scalar context cannnot return an empty list, and return () will in fact be an undef result (and hence false).

Do any others find their brains working this way? Or would everyone else consider "returns an array" and "returns an empty list" equally good or bad?