# after $dbh is obtained
{
    my $sth = $dbh->prepare
        "select
            hall_name,
            upload_date,
            uploaded_by,
            photo_id
        from hall_details
        where
            hall_id=?
            limit 1";

    sub details_from_id {
        my $id = shift;
        $sth->execute $id;
        $sth->fetchrow_hashref;
    }   # mod some error checking
}

##</code><code>##

my @hall_ids = 1..20;
my %details;
@details{@hall_ids} = map { details_from_id $_ } @hall_ids;