Question

我需要使用以下条件排除bidding_price列中的重复记录：

表：bid_account

要检查的栏目：

id = PRIMARY KEY
auction_id =每件商品的ID
  bidding_price =插入值（必须检查每个产品的重复性）
  bid_flag =必须始终等于以下值：＆＃39; d＆＃39;
bidding_type =必须始终等于:: ＆的值＃39; S＆＃39;

在bidding_price列中始终存在相同的记录，它不能具有相同的记录，具有相同的产品ID（auction_id）。

它不应该具有的示例：

auction_id |的 bidding_price
   ------ 10 ------------ 0.02
  ------ 10 ------------ 0.02
  ------ 11 ------------ 0.02
  ------ 11 ------------ 0.02

正确的是：

auction_id |的 bidding_price
   ------ 10 ------------ 0.02
  ------ 11 ------------ 0.02

我尝试使用以下命令：

DELETE ba
    FROM bid_account ba JOIN
         (SELECT ba2.auction_id, ba2.bidding_price, MAX(ba2.id) as max_id
          FROM bid_account ba2
          WHERE ba2.bid_flag = 'd' AND ba2.bidding_type = 's'
          GROUP BY ba2.auction_id, ba2.bidding_price
         ) ba2
         ON ba2.auction_id = ba.auction_id AND
            ba2.bidding_price = ba.bidding_price AND
            ba2.max_id < ba.id
WHERE ba.bid_flag = 'd' AND ba.bidding_type = 's' AND ba.auction_id = ba2.auction_id

问题是它删除了多条不应删除的记录，没有正确进行验证。我该怎么办？

Answer 1

ID是您表中的 PRIMARY KEY ，因此您可以MAX(id)成为您的预订ID，然后使用NOT IN按ID删除MAX(id)

你可以试试这个。

DELETE ba FROM bid_account ba
WHERE ba.id NOT IN
(
  SELECT max_id FROM 
    (
      SELECT auction_id, bidding_price, MAX(id) max_id
      FROM bid_account 
      WHERE bid_flag = 'd' AND bidding_type = 's'
      GROUP BY auction_id, bidding_price
    ) t
)

sqlfiddle：http://sqlfiddle.com/#!9/0f2e5/1

修改

如果您想获得最低价值的ID，可以在where子句的子查询中使用MIN(id)

DELETE ba FROM bid_account ba WHERE ba.id NOT IN ( SELECT min_id FROM ( SELECT auction_id, bidding_price, MIN(id) min_id FROM bid_account WHERE bid_flag = 'd' AND bidding_type = 's' GROUP BY auction_id, bidding_price ) t )

sqlfiddle：http://sqlfiddle.com/#!9/ffe92/1

Answer 2

以下声明应该为您提供所需的所有记录。

SELECT ba2.auction_id, ba2.bidding_price, MAX(ba2.id) as max_id
FROM bid_account ba2
WHERE ba2.bid_flag = 'd' AND ba2.bidding_type = 's'
GROUP BY ba2.auction_id, ba2.bidding_price;

not-in子句应该为您提供您不需要的所有记录。因此，从不在id中的bid_account中删除（#sub查询以获取所需的ID＃）和ba.bid_flag =＆＃39; d＆＃39;和ba.bidding_type =＆＃39; s＆＃39;应该删除重复的记录。

Answer 3

您可以使用PRIMARY KEY：ID删除它。它用于唯一标识删除操作的记录。请参阅此处的演示：http://sqlfiddle.com/#!9/603d56/1

它使用在子查询中选择ID（选择它两次将避免错误：无法指定目标表进行更新）。子查询与您的查询类似，它选择将保留的ID。使用NOT IN意味着删除子查询中不等于这些ID的其余行。

delete e.*
from bid_account e
where e.id not in (
select id from (
    select a.id
    from bid_account a
    join bid_account b
    on a.auction_id=b.auction_id
    and a.bidding_price=b.bidding_price
    and a.bid_flag=b.bid_flag
    and a.bidding_type=b.bidding_type
    where a.bid_flag='d' and a.bidding_type='s'
    and a.id < b.id) tt);

删除多个条件的记录

3 个答案: