More: What's returned from $sth-execute(); ?
Hi,
I see your point re:
Some code to illustrate:
printf Query: %s\n, $query;
my $sth = $dbh-prepare ($query);
$sth-execute();
# metadata information becomes available at this point ...
printf NUM_OF_FIELDS: %d\n, $sth-{NUM_OF_FIELDS};
print Note: query has no result set\n if $sth-{NUM_OF_FIELDS} == 0;
but what I really want to do is determine at an early stage if I have any
results at all in my result set. Actual reason for this is that I'm doing a
SELECT WHERE query and scanning my entrire DB for a session ID that
matches one read from a cookie. I then want to determine if this is a valid
session id and if not re-direct the user to a page saying unrecongnised
session id or something.
Thanks,
Jeff
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What's returned from $sth-execute(); ?
Hi, I've been using the return value of $sth-execute(); (in Perl DBI) to determine if I have a result set. I'm not using the value I get back but am assuming that if it's =1 then I have some results. Is this a safe thing to do with MySQL? And The results do actually seem to be correct for the number of records I get back. Should this be the case? Is it reliable? Thanks, Jeff - Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail [EMAIL PROTECTED] To unsubscribe, e-mail [EMAIL PROTECTED] Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
Re: What's returned from $sth-execute(); ?
At 16:15 + 1/10/03, Jeff Snoxell wrote:
Hi,
I've been using the return value of $sth-execute(); (in Perl DBI) to
determine if I have a result set. I'm not using the value I get back but am
assuming that if it's =1 then I have some results.
That's incorrect because it's valid for a result set to be empty (have
zero rows). Consider the result of SELECT * FROM t WHERE 1 = 0.
You don't need to use the return value at all. Check the metadata to
see if the number of columns is zero. If it is, there's no result set.
If it's 0, there is a result set.
Some code to illustrate:
printf Query: %s\n, $query;
my $sth = $dbh-prepare ($query);
$sth-execute();
# metadata information becomes available at this point ...
printf NUM_OF_FIELDS: %d\n, $sth-{NUM_OF_FIELDS};
print Note: query has no result set\n if $sth-{NUM_OF_FIELDS} == 0;
Is this a safe thing to do with MySQL?
And
The results do actually seem to be correct for the number of records I get
back. Should this be the case? Is it reliable?
If you mean, can you interpret the $sth-execute() result as a row
count, the DBI docs specifically discourage it.
Thanks,
Jeff
-
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http://www.mysql.com/manual.php (the manual)
http://lists.mysql.com/ (the list archive)
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Re: What's returned from $sth-execute(); ?
this should answer your question, from the DBI documentation http://search.cpan.org/author/TIMB/DBI-1.30/DBI.pm#execute sql,query,queries,smallint - hcir On Friday, January 10, 2003, at 02:55 PM, [EMAIL PROTECTED] wrote: I've been using the return value of $sth-execute(); (in Perl DBI) to determine if I have a result set. I'm not using the value I get back but am assuming that if it's =1 then I have some results. - Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail [EMAIL PROTECTED] To unsubscribe, e-mail [EMAIL PROTECTED] Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
