이전글, 다음글 날짜 순서대로 하는 방 채택완료

// 이전글, 다음글 링크
unset($prev);
unset($next);

// 윗글을 얻음
$sql = " select wr_id, wr_subject, wr_datetime from {$write_table} where wr_is_comment = 0 and wr_num = '{$write['wr_num']}' and wr_reply < '{$write['wr_reply']}' and wr_1 = '{$sid}' and wr_1 <> '' order by wr_num desc, wr_reply desc limit 1 ";
$next = sql_fetch($sql);
// 위의 쿼리문으로 값을 얻지 못했다면
if (!isset($next['wr_id']) || !$next['wr_id'])     {
    $sql = " select wr_id, wr_subject, wr_datetime from {$write_table} where wr_is_comment = 0 and wr_num < '{$write['wr_num']}' and wr_1 = '{$sid}' and wr_1 <> '' order by wr_num desc, wr_reply desc limit 1 ";
    $next = sql_fetch($sql);
}

// 아래글을 얻음
$sql = " select wr_id, wr_subject, wr_datetime from {$write_table} where wr_is_comment = 0 and wr_num = '{$write['wr_num']}' and wr_reply > '{$write['wr_reply']}' and wr_1 = '{$sid}' and wr_1 <> '' order by wr_num, wr_reply limit 1 ";
$prev = sql_fetch($sql);
// 위의 쿼리문으로 값을 얻지 못했다면
if (!isset($prev['wr_id']) || !$prev['wr_id']) {
    $sql = " select wr_id, wr_subject, wr_datetime from {$write_table} where wr_is_comment = 0 and wr_num > '{$write['wr_num']}' and wr_1 = '{$sid}' and wr_1 <> '' order by wr_num, wr_reply limit 1 ";
    $prev = sql_fetch($sql);
}

// 이전글 링크
$prev_href = '';
if (isset($prev['wr_id']) && $prev['wr_id']) {
    $prev_wr_subject = get_text(cut_str($prev['wr_subject'], 255));
    $prev_href = get_pretty_url($bo_table, $prev['wr_id'], $qstr);
    $prev_wr_date = $prev['wr_datetime'];
}

// 다음글 링크
$next_href = '';
if (isset($next['wr_id']) && $next['wr_id']) {
    $next_wr_subject = get_text(cut_str($next['wr_subject'], 255));
    $next_href = get_pretty_url($bo_table, $next['wr_id'], $qstr);
    $next_wr_date = $next['wr_datetime'];
}