nlafferty has asked for the wisdom of the Perl Monks concerning the following question:

This node falls below the community's threshold of quality. You may see it by logging in.

Replies are listed 'Best First'.
Re: UPDATE WHERE oid = $oid
by runrig (Abbot) on Jul 20, 2001 at 00:54 UTC 
    # Update oid with new timestamp
my $sql = <<"EOT";
update clock
 set time = ?
where oid = ?
EOT

my $upd_h = $dbh->prepare($sql);
$upd_h->execute($new_time, $oid);

# Get oid(s) with latest timestamp
# This could all be done in one select
# with either a subquery or ordering
# by descending time, but this is one way

# Get max timestamp
$sql = <<"EOT";
select max(time)
from clock
EOT

my ($time) = @{$dbh->selectcol_arrayref($sql)};

# Get all oid(s) with max timestamp
$sql = <<"EOT";
select oid
from clock
where time = ?
EOT

my (@oids) = @{$dbh->selectcol_arrayref($sql, {}, $time);

    [download]
[reply]
[d/l]
Re: UPDATE WHERE oid = $oid
by jepri (Parson) on Jul 20, 2001 at 00:54 UTC
    You need to read the manual first, then come back and ask some more questions.

    ____________________
    Jeremy
    I didn't believe in evil until I dated it.

[reply]
Re: UPDATE WHERE oid = $oid
by Wookie (Beadle) on Jul 20, 2001 at 01:17 UTC
    This is a terrible hack way to do it - but you could reduce it to one select by: 
    $sql='select oid,time';
$sql.='from clock';
$sql.='order by time';
$exec=$dbh->prepare($sql);
$exec=$dbh->execute()||die "Query Failed\n$sql\nError:\n$DBI::errstr";
while ($res=$exec->fetch) {
    $latest_oid=${$res}[0];
}

    [download]
    As the last record to come off this query should be the one with the latest time stamp - $latest_oid will have the corresponding oid.
    game(Wookie,opponent) eq 'Wookie' ? undef $problem : remove_limbs(arms,opponent);
[reply]
[d/l]
      You can order by 'time desc' and then the first oid's will be the ones with the latest timestamp.
[reply]

Back to Seekers of Perl Wisdom