Re: Determining if a DBI SELECT comes back empty

Not all DBDs set the statement handle before a fetch, but MySQL does. That means that you don't have to fetch *any* rows. For a purposefully verbose example:

if (my $rows = $sth->execute) {
    if ($rows==0) {
        print "Zero rows returned";
    }
    else {
        print "$rows rows returned";
    }
}
else {
   print "Failed execute: ". $sth->errstr;
}
$sth->finish;
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Note that the finish() is required here because you do no fetching. If one of the if's had a fetch, you'd omit the finish().

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Re: Re: Determining if a DBI SELECT comes back empty by tantarbobus (Hermit) on Dec 05, 2003 at 22:43 UTC
Not all DBDs set the statement handle before a fetch, but MySQL does But not always. If you create the statement with mysql_use_result rows() will no longer behave that way. Note that the finish() is required here because you do no fetching. If one of the if's had a fetch, you'd omit the finish(). If one had a fetch() and fetch()ed to the end of the result set. If you fetch 10 rows out of an 11 row result set you will still need to call finish on the sth	[reply]

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Re: Re: Determining if a DBI SELECT comes back empty
by tantarbobus (Hermit) on Dec 05, 2003 at 22:43 UTC

Not all DBDs set the statement handle before a fetch, but MySQL does

But not always. If you create the statement with mysql_use_result rows() will no longer behave that way.

Note that the finish() is required here because you do no fetching. If one of the if's had a fetch, you'd omit the finish().

If one had a fetch() and fetch()ed to the end of the result set. If you fetch 10 rows out of an 11 row result set you will still need to call finish on the sth

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