检查mysql中的行顺序

Question

需要一些关于mysql的帮助。

我有一个满是出价的表格，我需要检查来自同一个用户的出价是否超过3个

。

以下是一些代码：

$all = sql_get('select all bids from bids where auction_id = 1 order by amount asc');
$total = 0;

foreach ($all as $bid) {
  if ($bid->user_id == $user->id) {
    if (++$total <= 3) continue;
    $bid->burned = true;
    sql_store($bid);
    show_error('you cant have more than 4 bids one after another, the last bid was burned.');
  } else {
    $total = 0;
  }
}

有没有办法在单个查询中执行此操作？

Answer 1

SELECT user_id, CASE WHEN @user_id = user_id 
    THEN @rownum := @rownum + 1 
    ELSE ((@user_id := user_id) * 0) + (@rownum := 1) END AS rownum
FROM (  SELECT user_id
        FROM bids, (SELECT @rownum := 0, @user_id := NULL) AS vars
        WHERE auction_id = 1
        ORDER BY created DESC) AS h
HAVING user_id = '{$user->id}' AND rownum >= 3

只需将user_id解析为查询，您就会知道是否连续 3 。这假设您使用created列保存了创建行的时间。

Answer 2

为什么不进行计数查询并在WHERE子句中传递user_id？

$query = "SELECT COUNT(bids) AS total_bids FROM bids WHERE auction_id = 1 AND user_id = '$user->id' ORDER BY amount";