MySQL删除行直到某一点

Question

我正在为客户建立拍卖网站,我有一个问题,我需要从投标表中删除投标,直到某一点,该点由投标人数或底价确定.

让我进一步解释.我有一个数据表:

Bidder1 $7,250.00  Sat 21 Jul 2012 12:25:44
Bidder2 $7,000.00  Sat 21 Jul 2012 12:26:34
Bidder1 $6,250.00  Sat 21 Jul 2012 12:25:44
Bidder2 $6,000.00  Sat 21 Jul 2012 12:26:11
Bidder1 $5,250.00  Sat 21 Jul 2012 12:25:44
Bidder2 $5,000.00  Sat 21 Jul 2012 12:25:34
Bidder2 $1,100.00  Sat 21 Jul 2012 12:23:53
Bidder1 $1,000.00  Sat 21 Jul 2012 12:22:33
Bidder1 $550.00    Sat 21 Jul 2012 12:22:33
Bidder2 $500.00    Sat 21 Jul 2012 12:22:23
Bidder2 $100.00    Sat 21 Jul 2012 12:22:23

正如你所看到的那样,有2个竞标者正在努力解决它.现在每个投标人都可以随时取消他们的出价,但是,如果bidder2取消他们的出价,系统会将拍卖中的所有出价标记为已取消(客户要求),而不仅仅是他们的最新出价.如果是这种情况(bidder2取消他们的出价),那么bidder1的出价应该回滚到1000美元,这是拍卖的底价(因为你应该知道因为bidder1,550美元和1000美元连续出价) ).

继续我所希望的只是棘手的一点而不是不可能的一点.假设我有3个投标人:

Bidder1 $7,250.00  Sat 21 Jul 2012 12:25:44
Bidder2 $7,000.00  Sat 21 Jul 2012 12:26:34
Bidder3 $6,250.00  Sat 21 Jul 2012 12:25:44
Bidder2 $6,000.00  Sat 21 Jul 2012 12:26:11
Bidder1 $5,250.00  Sat 21 Jul 2012 12:25:44
Bidder2 $5,000.00  Sat 21 Jul 2012 12:25:34
Bidder3 $1,100.00  Sat 21 Jul 2012 12:23:53
Bidder1 $1,000.00  Sat 21 Jul 2012 12:22:33
Bidder1 $550.00    Sat 21 Jul 2012 12:22:33
Bidder2 $500.00    Sat 21 Jul 2012 12:22:23
Bidder2 $100.00    Sat 21 Jul 2012 12:22:23

如果bidder2取消了他们的出价,那么我需要回滚到bidder3的最新出价,但仍然以bidder1获胜.

任何指导表示赞赏.

Answer 1

首先统计总数 投标人数量

$result = mysql_query("select distinct(bidder_id) from table where bid_id=1");

//考虑我们要删除 bidder_id=2 出价

if(mysql_num_rows($result) == 2 ) {
 //select min bid of bidder
 $row = mysql_fetch_row(mysql_query("select * from table where bidder_id=2 order by bid_price asc limit 1"));

 $bidder_min_amount = $row['bid_price'];
 $bidder_min_id = $row['id'];

 //find out other bidder min bid id 
    /*
    Bidder1 $7,250.00  Sat 21 Jul 2012 12:25:44
    Bidder2 $7,000.00  Sat 21 Jul 2012 12:26:34
    Bidder1 $6,250.00  Sat 21 Jul 2012 12:25:44
    Bidder2 $6,000.00  Sat 21 Jul 2012 12:26:11
    Bidder1 $5,250.00  Sat 21 Jul 2012 12:25:44
    Bidder2 $5,000.00  Sat 21 Jul 2012 12:25:34
    Bidder2 $1,100.00  Sat 21 Jul 2012 12:23:53
    Bidder1 $1,000.00  Sat 21 Jul 2012 12:22:33
    Bidder1 $550.00    Sat 21 Jul 2012 12:22:33
    Bidder2 $500.00    Sat 21 Jul 2012 12:22:23
    Bidder2 $100.00    Sat 21 Jul 2012 12:22:23
    //may be first case like this
    Bidder1 $75.00    Sat 21 Jul 2012 12:22:33
    */ 
    //finding out if Bidder1 $75.00 exist
    $row = mysql_query("select * from table where bid_price <= $bidder_min_amount and bidder_id!=2 order by bid_price asc");
    if(mysql_num_rows($row) > 0 ) { 
     mysql_query("delete from table where id > ".$row['id'] );
    } else {
      $row = mysql_query("select * from table where bid_price >= $bidder_min_amount and bidder_id!=2 order by bid_price asc");
      if(mysql_num_rows($row) > 0 ) { 
         mysql_query("delete from table where id > ".$row['id'] );
        }
    } 
} //first condition complete if total bidder is 2
else {
    //if n bidders just remove the bids of bidder
    mysql_query("delete from table where bidder_id=2");
}

希望这会对你有所帮助。